Heat 1 tablespoon oil in a pan. Add ½ teaspoon mustard seeds and let them crackle on low heat.
When they start crackling, add ½ teaspoon urad dal and ½ teaspoon cumin seeds.
Saute till the urad dal turns golden stirring often on low heat.
Then add 5 to 6 curry leaves (chopped or kept whole), ½ teaspoon finely chopped ginger, 1 dry red chili (seeds removed) and 1 green chili (chopped). You can also add a pinch of asafoetida at this step.
Stir and then add ¼ cup chopped onion. Saute till the onions turn translucent stirring often on low heat.
Then add the crumbled idli. Also add a bit of salt as per taste. Mix very well and saute for a minute or two.
Then switch off the heat. Lastly add 1 to 2 tablespoons of chopped coriander leaves. At this step, you can also add some grated coconut.
Mix again and serve idli upma hot with some coconut chutney or lemon pickle. While serving you can drizzle some lemon juice.
Notes
The recipe can be easily doubled or tripled.
If you are using leftover idlis that have been refrigerated then first bring them to room temperature before using them in the dish.
If you are using freshly prepared idli then use them once they become warm.
You can use any neutral-flavored oil.
You can vary the amount of spices as per your taste.
Idli podi can also be added.
To make it more nutritious you can opt to add some grated veggies, boiled peas, nuts like cashews and some roasted peanuts.