Soak peanuts and chana dal in hot water for 30 minutes.
Crush green chillies and garlic coarsely using a mortar and pestle. Keep aside.
In a bowl, whisk curds with 1 cup water.
In another bowl, mix besan with ½ cup water to make a smooth paste.
Add this to the buttermilk and whisk well. Set aside.
Heat oil in a pan. Add mustard seeds, cumin seeds, asafoetida, and curry leaves.When they crackle, add the chilli-garlic paste and sauté for a minute.
Add the soaked peanuts and chana dal. Cook on low heat until they are almost done.
Add chopped spinach, turmeric powder, red chilli powder, and salt. Mix well, cover,and cook until spinach, peanuts, and chana dal are cooked.
Add the prepared buttermilk-besan mixture. Stir well and cook on low flame for 4–5 minutes,stirring occasionally.
Servehot with steamed rice.