Idli recipe with video and step by step photos. This is a tried and tested method to make soft and fluffy idlis at home. If you are new to Indian cuisine, then read on. If you are not new to Indian cuisine then Jump to recipe.
What is idli
Idli is a soft, pillowy steamed savory cake made from rice and lentil batter. The lentils used in making idli are urad dal (black gram). Idli is a traditional breakfast made in every South Indian household including mine. Idli is popular not only in the whole of India but outside India too. Idlis are naturally vegetarian, vegan, gluten free and makes for one of the healthiest breakfast.
How is idli batter made
There are two ways you can prepare idli batter:
- One method uses idli rice along with urad dal. Idli rice is parboiled rice and used specifically for making idli and dosa.
- The second method uses idli rava with urad dal. Idli rava is coarsely ground idli rice and is easily available in shops and online. I have shared the method of making idli with idli rava in this post – Idli made with idli rava.this idli recipe post shares the Method of using rice to make the batter. Generally only idli rice is used to prepare idlis. But not everywhere in India, is idli rice easily available. here the recipe shares the method of using two kinds of rice. One is parboiled rice and other is a regular rice. You can even make idli with short grained rice. On occasions, my mom makes one of the best idli with parmal rice. She only uses parmal rice and split urad dal. No methi seeds, no baking soda or anything. At times I also make idli with the traditional method of using only idli rice.
How is idli batter ground
For making a simple traditional idli, first both the rice and the urad dal are soaked separately for 4 to 5 hours. Then the lentils (urad dal) are ground to a soft, fluffy batter. Later the rice is ground to a semi fine consistency. Both the batters are mixed and allowed to ferment. The grinding of the batters, can be done in a stone wet grinder or in a mixer-grinder.
Grinding in a stone grinder is helpful if making a large quantity of idli batter. The advantage of grinding in a stone grinder is that the urad dal batter gets ground really well and thus the idli batter ferments also well.
I have both a stone grinder and a mixer grinder. For smaller quantities I use the mixie for grinding and for larger quantities I use the stone grinder. Both work differently and the amount of water to be added also varies.
However, everyone does not have a stone grinder. So, here I have shared the detailed method on how to grind the batter in a mixer grinder with lots of tips and suggestions in the step by step pics.
Tips for idli batter fermentation
Fermentation is a key factor in getting soft, light and fluffy idli. For proper fermentation of idli batter a warm temperature is apt. In cold climates, fermentation does not happen well. I get a lot of queries on how to ferment idli or dosa batter in winters. So I have Summarized my experiences in the following points below:
- Keep the idli batter bowl in a warm place – e.g near a heater or in a warm place in your kitchen.
- You can also preheat your oven at a low temperature (80 to 90 degrees celsius) for about 10 to 15 minutes. Then switch off the oven and keep the batter bowl inside – I use this method when it becomes very cold outside.
- Alternatively, if your oven has lights, then keep the lights on and place the batter inside.
- Addition of a bit of sugar does help in fermenting the batter. So I use this method at times in the winters here.
- During winters, skip adding salt to the idly batter as salt retards the fermentation process. Its better to use rock salt or sea salt. I always use rock salt in the idli batter.
- In winters, keep the batter for a longer time to ferment, like 14 to 24 hours.
- Do remember that even if you do not see the batter doubled or tripled, you should see tiny bubbles in the batter. You should also get the typical faint sour fermented aroma from the idli batter.
- You can even add ¼ to ½ tsp of instant yeast (dissolved in 2 to 3 teaspoons of water) 30 to 45 minutes before you steam the idli. But do this method when the batter has not fermented well. The downside of this method is that you have to use all the batter at once. If you refrigerate than the batter gets too yeasty and sour.
- You can also add ¼ to ½ baking soda and then ferment the batter in cold seasons.
- Addition of methi seeds (fenugreek seeds) also helps in fermentation.
- Urad dal has to be ground really well. Urad dal batter has to be soft, light and fluffy. So I suggest to grind both urad dal and rice separately to get soft and fluffy idli. A well ground urad dal batter also helps in fermentation.
- Also do remember to add the correct amount of water in the batter. If the water is less, then the idli will become dense.
How is idli made
The ground idli batter is fermented overnight or for 8 to 9 hours. Then the fermented idli batter is steamed in an idli pan. The steaming time is generally from 12 to 15 minutes. Idli should never be over steamed as then they become dry and dense. Idli pans or idli moulds are easily available in shops and even online.
Variations with idli batter
There are many possible variations you can do with a basic idli batter. You can add lentils like moong dal and make moong dal idli. Even millets, flattened rice (poha) can be added to the batter. Oats can also be added. I have shared Oats idli recipe. experiment with proportions and then decide on the one which gives you the best idli in terms of texture and taste.
Other variations are making stuffed idli, idli sandwich or idli pizza etc. I have shared some traditional idli variations like:
Difference between idli batter and dosa batter
Both idli and dosa batter are made from rice and lentils. Idli batter is more thick in consistency than a dosa batter. To make dosa, the batter is spread on the tava (griddle) and thus needs to have a slight flowing and spreadable consistency.
- For idli batter the ratio to be used is 4:1 of rice and lentils. From this 4:1 ratio of idli batter, you can even make dosa. I always use the proportion of 4:1 to make idli. the proportion of rice and urad dal is always a matter of controversy. So I suggest experiment with different types of rice and come to your own standard measurements which will give you perfect idli.
- For dosa, the ratio that is generally used is 3:1 of rice and lentils. Also do not that for making dosa batter, you can easily use rice like sona masuri, parmal rice or can even use idli rava instead of idli rice.
Idli is a breakfast I have grown up with. On every weekends, soaking rice & lentils, then preparing idli batter was a regular ritual. Every sunday, I knew we would get piping hot idli or soft dosa for breakfast along with chutney and sambar.
Initially, when preparing idli for the first time, I ran into problems. But now after so many years of experience, I can make really good idli and dosa.
For a more softer texture in idli, I always add thick poha (flattened rice) or cooked rice. This is optional and you can skip adding poha. You could also steam idli in a damp muslin cloth. Steaming idli this way also gives a soft texture.
With this recipe of idli batter, you can also make crisp dosas. You can use this batter on the same day, the batter is fermented to make dosas. Or else you can make idli on the first day and make dosa or uttapams on the second day. serve idli hot or warm with sambar and coconut chutney.
I have also attached a video (2.08 minutes quick video). In the video I have shown the preparation of idli with 2 cups of idli rice. But you can even use 1 cup of regular rice and 1 cup of parboiled rice.
Idli recipe video
How to make idli and idli batter
Soaking rice and dal for making idli
1. In a bowl or pan take 1 cup parboiled rice and 1 cup regular rice. Here I have used sona masuri rice along with parboiled rice. Instead of this proportion, you can also use overall 2 cups of idli rice OR 2 cups of parboiled rice (as shown in video above).
2. Pick and then rinse both the rice varieties for a couple of times. Drain and keep aside.
3. Take ¼ cup thick poha in a bowl.
4. Rinse the poha once or twice with water.
5. Then add the poha to the rice. Add 2 cups water. mix very well and keep aside covered to soak for 4 to 5 hours.
6. In a separate bowl take ½ cup urad dal along with ¼ teaspoon fenugreek seeds.
7. Rinse a couple of times.
8. Add 1 cup water. Cover and soak for 4 to 5 hours.
Making idli batter
9. Before grinding, drain the urad dal, but don’t throw away the water. Reserve the soaked water.
10. In a wet grinder jar, add the urad dal. initially add ¼ cup of the reserved water.
11. And grind the urad dal for some seconds. Then add ¼ cup water and continue to grind. The batter should be light and fluffy when completely ground.
12: pour the urad dal batter in a deep pan or bowl.
13: drain the rice & poha and add them in the wet grinder jar. I usually grind in two parts. Depending on the capacity of your mixer-grinder you can grind in two to three parts. If the mixie gets heated up while grinding, then stop and let it cool. Then continue with the grinding.
14: use the urad dal strained water or regular water to grind the rice and poha too. add water in parts and grind. The rice can have a fine rava like consistency in the batter. A smooth batter is also fine. I usually add a total of ¾ cup of water while grinding rice. The rice batter should not be too thick or thin.
15: now pour the rice batter in the bowl containing the urad dal batter.
16. Add 1 teaspoon rock salt. Mix very well with a spoon or spatula. If you live in a cool or cold region, then do not add salt. Add salt later once the fermentation is done. If you live in a hot or warm climate, then add salt as it does not allow the batter to get over fermented in the time duration of 6 to 8 hours.
17. Cover the bowl or container with a lid and keep the batter in a warm place. It should be left undisturbed for 8 to 9 hours. Don’t use an air-tight lid. In colder climate, keep the batter for a longer time – from 12 to 24 hours.
18. The batter the next morning. It will ferment and increase in volume.
Steaming idli from idli batter
19. grease the idli mould with oil. Gently and lightly swirl the batter. Don’t overdo. Now with a spoon pour portions of the batter in the greased idli moulds.
20. Take your idli steamer or pressure cooker or electric cooker. Add some 2 to 2.5 cups water and heat the water. keep the idli mould in the steamer or pressure cooker. Steam for 12 to 15 minutes. Timing will vary depending on the kind of equipment you have used. If using a pressure cooker, then cover the pressure cooker with its lid. Remove the vent weight/whistle from the lid. Steam the idlis for approx 12 to 15 minutes.
21. Check for doneness by inserting a toothpick. If it does not come out clean, then keep again for a few more minutes. When done remove the idli mould from the cooker. Don’t overcook as then they become dry. Dip a spoon or butter knife in water and slid them through the idlis. Remove and place the idlis in a warm container like a casserole.
22. Serve Idli hot or warm with sambar and coconut chutney.
How is idli served
- Idli is served with coconut chutney and sambar. Idli is dunked in sambar and eaten. There are quite a number of both sambar and coconut chutney varieties that one can make to go with idli.
- Idli is also served with idli podi or gun powder. Idli podi is a condiment powder made with lentils and spices. If you do not have time to make sambar, then you can just serve idli with coconut chutney and idli podi. Idli can also be served with curd which has been spiced and tempered.
What to do with leftover idli
At times there is an extra or surplus of idli left. You can use these idli the same day to make a new recipe or refrigerate them and use the next day. With leftover idli you can make the following recipes.
- Idli manchurian – idli stir fried with veggies in a spicy, sweet and sour sauce.
- Masala idli – idli sautéed in a onion and tomato masala.
- Idli chilli – spicy Indo Chinese recipe of idli in a spicy and sour sauce.
- Idli upma – tasty variety of upma made with idli.
idli recipe
INGREDIENTS
- 1 cup regular rice + 1 cup parboiled rice or 2 cups idli rice or 2 cups parboiled rice
- ½ cup whole or split urad dal or 120 grams whole or split urad dal (husked black gram)
- ¼ cup thick poha or 20 grams thick poha (flattened rice)
- ¼ teaspoon fenugreek seeds (methi seeds)
- 2 cups water for soaking rice
- 1 cup water for soaking urad dal
- ½ cup water for grinding urad dal or add as required
- ¾ to 1 cup water for grinding rice or add as required
- 1 teaspoon rock salt (sendha namak) or sea salt
- oil as required to apply to the idli moulds
- 2.5 cups water for steaming idli
INSTRUCTIONS
soaking rice and dal
- Pick and rinse both the regular rice and parboiled rice.
- Rinse the poha and add to the rice.
- Add water. Mix well. Cover and keep the rice + poha to soak for 4 to 5 hours.
- In a separate bowl, rinse the urad dal and methi seeds a couple of times.
- Soak the urad dal with methi seeds separately in water for 4 to 5 hours.
making idli batter
- Drain the soaked urad dal. Reserve the water.
- Grind the urad dal, methi seed with ¼ cup of the reserved water for some seconds. Then add remaining ¼ cup water. Grind till you get a smooth and fluffy batter.
- Remove the urad dal batter in a bowl and keep aside.
- Grind the rice in batches to make a smooth batter.
- Mix both the batters together in a large bowl or pan. Add salt and mix well.
- Cover and let the batter ferment for 8 to 9 hours or more if required.
- After the fermentation process is over, the idli batter will become double in size and rise.
steaming idli
- Grease the idli moulds.
- Pour the batter in the moulds and steam the idli in a pressure cooker or steamer.
- If using pressure cooker remove the vent weight (whistle).
- Steam for 12 to 15 mins or until the idli is done.
- Serve the steaming hot idli with coconut chutney and sambar.
- Remaining batter can be stored in the refrigerator for a couple of days.
Hi Dassana,
I have tried this measurement with mixer grinder for few times now. Thanks a ton. It turned out to the best that I could make. Now I bought a wet grinder. Will the same measurement work for soaking and grinding? Also, the amount of the water used to soak matters?
You mentioned, don’t use air tight container for fermentation. Did you really mean don’t use or “use”? I have been thinking all these days that we have to use air tight container for fermentation. I live in Bangalore and these days it is really cold.
Regards,
Jayasuda.
hi jayasuda, firstly thank you for the review and rating on idli recipe. glad to know. your queries answered below.
1. for a wet grinder, you will need to add some more water while grinding. the urad dal really becomes fluffy and light like whipped cream in a wet stone grinder. for 1/2 (half) cup of urad dal, i add 1.5 cups water. for 2 cups rice, i add 2.5 cups water. but add water in parts when grinding urad dal, so that it becomes nicely fluffy and increases in volume.
2. yes, the amount of water does help in fermentations also yields soft idli. a lid has to be used, but it should not be air-tight. a simple plain lid just covering the bowl is fine.
3. to ferment in a cold climate, you can preheat the oven for 20 minutes at a temperature of 50 to 60 degrees celsius. switch off the oven. then keep the bowl inside. if your oven has a lamp, then keep it on and place batter bowl inside. do not preheat if the oven has a lamp. if the oven has a ferment function, then use that. hope this helps.
regards
dassana
Good information &it is so useful to Food business starters ..
Hi,
Can we make idli and dosa batter with Basmati rice? That’s the only variety i have with me and I don’t have an indian store in the vicinity.
with basmati rice, you can try. but it can be tricky to get the right texture depending on the type of basmati rice. still, you can give a try. just grind the urad dal very well till the batter becomes fluffy and light. half the work is done when the urad dal is ground really well. hope this helps.
Madam are u taking cooking class.
If yes then please share me details
I am interested in class
hi nilesh, i am not taking any cooking class. all the recipes that i know of i have shared on the website.
Hi…
I had a couple of questions:
1. If I use 2:1 ratio of rice:urad dal, how much poha and fenugreek seeds should I use?
2. A friend told me the more urad dal I use, the more softer the idli will be. Is it true?
you can use the same amount of poha and fenugreek seeds for the ratio you have mentioned. more urad dal gives a different taste in the idli. the taste of urad dal is felt distinctly in idli. but the idlis are softer with more urad dal if they are ground to a smooth fluffy batter. hope this helps.
Thank you!
Sometimes I tend to use 3:1 ratio of rice:urad dal. How much poha and fenugreek seeds should I use for this proportion?
Also, can I use poni raw rice for idily? Is poni raw rice and basmati rice the same? I don’t know the difference between them that’s why I am asking.
welcome shinu. for 3:1 ratio of rice and urad dal add about 20 methi seeds and 1/4th cup thick poha.
you can easily use poni rice for idli. both raw and parboiled ponni rice will work. basmati rice is different than ponni rice. ponni is a medium grained rice whereas basmati is long-grained aromatic rice. you can ask any recipe doubt or query you have. no problem ????
Hi, I followed your recipe and idli’s turned out nice and soft; however they hd a strong Urad Dal taste. What can I do if the remainder batter? Should I reduce the Urad Dal quantity next time? I used a wet grinder could it be due to time for which I let Urad Dal grind (about 20 mins)?
ami, could be due to the quality, freshness of the urad dal. i have also used wet grinder for this proportion of urad dal and i did not get any strong taste coming from the dal. generally, the taste of urad dal is not felt, unless their proportion is more. the rice and urad dal proportions in this idli recipe is a balanced one and does not give the typical urad dal taste & flavor. you can try changing the brand and buy fresh urad dal which is still within its shelf period. you can even reduce the quantity of urad dal next time if using the same brand. hope these suggestions help.
Thank you!! I think it may be because the Urad Dal I used is old. Your recipe did yield the fluffiest idli’s I have ever been able to make. Will try with a new Urad Dal batch.
thanks for letting me know ami. with fresh urad dal the taste will be better.
Hi, I tried the poha idli it came out good but quite soft..I made the regular idli and I did ferment it well I used 2 cups of idli rice but it was too dense more like a bread..and on the second day it was even harder, what do you think is wrong?
Below is the recipe I usually make this and it comes out fine, but wanted to ty yours, pls tell me what you think went wrong as would like to try it again, thanks.
Idli recipe
Soak overnight
1 cup idli rice
1/4 cup dal
Next day
1/2 cup poha soak 1 hour before grinding
Grind all together with water add salt and keep outside for it to rise then keep in fridge and next day take out and keep before steaming.
thanks nikita. poha idli is soft. hardness or denseness is due to less water. sometimes event though the batter is fermented well, less water in the idli batter can make the idli dense. addition of water also depends on the type and quality of rice used. the batter has to be thick but of a pouring consistency. in your recipe you have used more amount of poha which will help in making soft idlis. also, proportion of rice and urad dal does not make difference if denseness or hardness or softness is considered. but taste wise there will be a difference. one more point is to note is that grind the urad dal really well. a smooth and fluffy urad dal batter helps in fermenting the batter well and also making the idlis soft.
????????idli was sooo soft
thanks kavya for this super feedback and the rating.
Hello,
Love to visit this site every now and then. I love the way you explain every step and methodically share them in picture form.
I’ve made rave idly, beetroot rasam, tamarind rasam and will explore more.
BTW, your Goan recipes are pretty authentic – this is coming for a Goan.
Sincere thanks!!
Regards,
Suyash
thanks suyash for the feedback on the recipe presentation and the reviews on the recipes. my mother is from goa, hence the authenticity. thanks again and happy cooking.
Hello mam, can we use regular salt in the place of rock salt ?
you can, but if living in cold place then avoid using iodized salt.
Hello! I am so homesick for India after watching your video! I have been so blessed for the opportunities to make 2 spiritual pilgrimages to Southern and Northern India. I would LOVE to be able to replicate idli but I have none of the equipment needed. Would you be able to recommend where I could purchase all the needed equipment and approximate cost of each of the pieces?
Thank you very much for your information and suggestions
I am a vegan chef and look forward to participating more on your site and recommending my students to you as well.
Namaste!
Lila
namaste, i can understand lila. to make the idli batter, you can easily buy a mixer-grinder from amazon.com. it will also help you to make various chutneys that you can savour with idli or dosa. you can even buy a table top stone grinder which is exclusively meant for making idli or dosa batter or medu vada batter. you can check on amazon. you will get plenty of options there with customer reviews and prices. i am using preethi 750 watts blue leaf mixer-grinder. wish you all the best.
Can I add 1 cup idli rice and 1 cup millets? i add millets to dosas and they turn out pretty well.. Not sure about idlis..
you can add. it will work. but also add some urad dal to give some fluffiness in the idlis.
Hello mam, plz help its been two days my idli batter z nt showing any sign of fermentation. I am living in delhi so its pretty cold here. Yesterday i kept the batter in hot water bowl for a while bt today i checked its still not fermented. Plz help mam i really wanna make idli.
charu, keep the batter near a heater or keep in the sunlight, if you get any. you can also cover the batter with a warm kitchen towel. don’t worry. sometimes it does take 3 days for the batter to ferment. hope these tips help.
Can i add baking soda or eno salt?
if the batter ferments well then there is no need to add baking soda or eno. if the batter has not fermented well, then you can add eno or baking soda.
Hi,
Does it make any difference if we use split urad dal in place of whole urad dal for given measurements.Do we need to make double the amount of split urad dal.
Thanks and regards
Welcome Yashwin. Use the same amount. You can use split urad dal. I also use it at times to make idli or dosa.
thanks alllottttttt ma’am
ur gr8
thanks alllottttttt
Welcome Divyanshi. Thanks for your kind words.
thanks a lot for suggesting such a wonderful recipe of idli
Welcome Divyanshi
Ma’am please tell me the recipe of sambar
it would be a great hlp
Divyanshi, you can check the sambar recipes collection here – https://www.vegrecipesofindia.com/sambar-recipes-sambar-varieties/
your recipe gave melt in mouth idli’s with out use of fruit salt or soda bi carb which is great. thanks a lot. small tips u write like using reserved water and salt in hot/ warm weather make big difference to end result. looking forward to trying more of your recipes.
Welcome Meenal. Thanks for your positive feedback on Idli Recipe. Glad to know that tips are helpful.
These days, when I make the batter, it blows a lot. After keeping in fridge, still it keeps on fermenting.Is it because I am using poha (flattened rice at good quantity) What does poha help in making soft idlis and how much should be added
The proportion I am using is 3.5 glass rice, 3/4 glass dal and one glass poha
Please help!!!!
its not due to poha. poha just helps in making the idlis soft. for the proportion you are using 1 glass poha is fine. but you can still add less poha like half a glass of poha. as soon as the batter is fermented keep in fridge. this way the batter won’t get over fermented.
This recipe turns out super tasty dosas too . It has turned dosas into my fave breakfast option ☺️☺️ Thanks a ton Dassana
Welcome Neelu. Yes, this recipe gives good dosas also.
Help, please. My idlis didn’t get fluffy and the didn’t rise when steaming. I thought my batter was well fermented. I used 1 cup of Indian long grained rice and 1 cup of parboiled rice. What can I do better? The cabbage chutney and the beetroot chutney from this site were excellent with the idlis. Thank you!
sari, if the idlis do not rise, then it could be more water is needed in the batter or could be due to the batter not getting fermented. the batter should have a pleasant sour aroma and you should see tiny bubbles in it. also it should double or triple depending on how warm are the temperature conditions in your city. if you see that the batter has not risen or no sour aroma, then keep it for some more time. it does get fermented eventually. in winters, i have even kept the idli batter to ferment for 22 hours. you can even keep the batter in a warm place eg near a heater or in a lit oven.
thanks for the feedback on the cabbage chutney and beetroot chutney recipes.
I did see tiny bubbels and the the batter smelled sour, but still my idli’s didn’t get fluffy. After reading your reply, I let the rest of the batter ferment for three days and the idli’s turned out soft and fluffy!
welcome sari. at times the batter does smell sour, but it is faintly or less sour as compared when the batter ferments well. glad that the idlis turned out soft and fluffy.
Hi,can I use just regular basmati rice(2cups) instead of using parboiled rice+ regular rice
Megha, with basmati rice depending upon its type the idlis can become dense or sticky. So I would not suggest only to use basmati rice. Instead you can use sona masuri or parmal rice.
Hi Dassana!
Let me just say- there is not a single recipe of yours that didn’t turn out exquisite. I totally love your recipes
About the idlis I wanted to ask if I can store the batter for couple of days in refrigerator.
Look forward for your reply!
Ayesha
Thanks Ayesha for your positive feedback on recipes. Yes you can store idli batter in fridge for few days. It stays good for about a week.
Hello Dassana,
Please help with 3 queries :
1. what is parboiled rice ? Is it easily available in India ? If yes then by what name ?
2.Urad dal is urad dhuli ?
3.poha thick in case if any other like regular poha is available in market and specifically its not mentioned thick poha can we use it or by anyother name if it is popular in Indian stores ?
Thanks
Megha.
1. parboiled rice is easily available in shops as well as online. its called as ukda or sela chawal.
2. you can use urad dhuli dal.
3. you can use any variety of poha. i have used thick poha.
Hello can i freeze the batter for later use?
Geeta, i have never freezed. so i don’t know the results after freezing the batter.
Thank you so much for your recipe. I did Idlis first time and turned out to be really good.
Also I would like to add note, for places like London, time for fermentation would be around 36 hours (in around march April, without help of oven)
Welcome Manasi. Thanks for sharing this timing. It help definitely help readers from london.
Thanks for the recipe…idlis came out perfect,soft & delicious! Excellent recipe????
thanks rima for this feedback. nice to know.
How many idlis can be made if I follow these measurements??
20 to 25 idlis.
First time making idlis from scratch.. Turned out soft and fluffy! Thanks so much!
Welcome Rheena. Glad to know this.
Hi ur recepies are no wonder mouth watering I am making idli for first time was wondering that for how much time I have to boil rice for the parboiled rice and also what difference it makes TIA
thanks pranjali. parboiled rice is commercially made and you have to buy it from shops.
Hello mam!!
Firstly would like to thank u from bottom of my heart for such detailed n step by step recipes.i tried many n all came out well.also I make tiffins following ur recipes.though my idlis come out soft but in a few minutes Dey devolop a dry layer on top n r no more soft.i follow exactly wt u specified except fr salt..I use regular ashirwad salt 1tsp n baking soda 1/4th tsp.plz correct me
thanks a lot tasneem. its best to use salt which is not iodized. even sea salt which is not iodized works. i am not exactly sure why the dry layer. only one thing i can guess is that the idlis have been steamed too much. if they are steamed too much, then they become dense and dry from top.
i will be adding a video in some weeks, which shows the process of steaming idlis. you can check the video on my youtube channel here whenever i edit and upload it – https://www.youtube.com/user/vegrecipesofindia