Make a paste of grated coconut and green chillies by adding little water. Set aside.
Mix the rice powder in half cup of water and keep aside.
Beat the curd well and add the water to make butter milk, keep aside.
Add the ground paste, rice powder water, salt and mix well.
Heat oil in a deep bottomed pan. Add mustard, fenugreek, cumin seeds. Let them splutter, then add asafoetida, turmeric powder and curry leaves. Sauté for a minute.
Add onions, chopped fenugreek leaves and fry for a minute. Add chopped tomatoes and cook till soft.
Add the butter milk mixture and cook on a low flame stirring continuously.
Let the liquid come to boiling point. When it starts boiling switch off the flame immediately.
Cover lid and let it sit for few minutes and allow the liquid to absorb the flavors.
Serve with steamed rice.