Rinse it very well. Peel and chop in medium to slightly large pieces. You can even rinse after chopping. You will need 3 cups chopped tapioca.
Add the chopped tapioca in a 2 litre pressure cooker. add 2 cups water. Also add ½ teaspoon salt.
Pressure cook on medium flame for 2 whistles or for 12 to 14 minutes. when the pressure settles down, open the lid.
Drain all the water. Cover and keep the tapioca aside.
making coconut paste
Meanwhile when the tapioca is getting pressure cooked, take ½ cup grated coconut in a grinder jar.
Add ½ teaspoon tamarind and ¼ to 1/3 cup water.
Grind to a smooth paste. Keep coconut paste aside.
making tapioca curry
Meanwhile heat 2 tablespoons coconut oil in a pan. Lower the flame and add ½ teaspoon mustard seeds and let them crackle.
Then add 1 inch cinnamon, 2 green cardamoms, 2 cloves, 8 fenugreek seeds (slightly crushed) and 1 to 2 dry red chilies (halved and seeds removed).
Fry till the red chilies change color.
Then add ¼ cup sliced pearl onions or shallots and 2 teaspoons finely chopped ginger.
Add 8 to 10 curry leaves (whole or chopped). mix well.
On a low flame sauté till the pearl onions turn translucent.
Then add ¼ teaspoon turmeric powder, ¼ teaspoon red chilli powder, ¼ teaspoon black pepper powder, ½ teaspoon cumin powder and ½ teaspoon coriander powder. mix very well.
Now add the coconut paste. mix again.
Stirring often, sauté coconut paste till it thickens and you see oil releasing from the sides.
Add 1 to 1.5 cups water. 1.5 cups water makes for a slightly thin curry and goes very well with rice. So if serving this kappa curry with rice, then you can make a slightly thin curry. For chapatis or parottas, you can make medium or thick gravy. For a medium consistency add 1 cup water. For a thick consistency add ½ to 2/3 cup water.
Season with salt as required.
Mix very well and simmer for 2 to 3 minutes.
Then add the boiled kappa or tapioca. mix again.
On a low flame simmer tapioca curry for 7 to 8 minutes. To thicken the gravy a bit, you can also mash a few tapioca pieces with a spoon.
Switch off the flame and then add 2 tablespoons chopped coriander leaves. Mix well.