Wash and drain off the tapioca pearls. There is no real soaking involved in water. Keep it covered for 6-8hrs or overnight.
The tapioca pearls should be squishy and disintegrate it when pressed. Add curd to this and mix it gently.
Meanwhile heat a cast iron skillet and heat oil. Add cumin seeds and let them splutter. Add curry leaves, green chillies and ginger. Fry for a few seconds.
Add diced potato and fry on low flame for 5-6 mins. Add salt as needed and continue frying on low flame for another 3-4 mins.
Add coarsely powdered roasted peanuts to the tapioca pearls, salt as needed and mix them up gently.
As potatoes are cooked to ¾th, add prepared tapioca pearls.
Stir-fry the tapioca pearls and cook them on low flame for 4-5 mins. Slowly the pearls begin to turn transparent. Cook for another couple of mins, check for doneness.