Pressure cook the soaked lentil with turmeric powder, chopped ridge gourd, onion, tomato, green chilies and 1 & 1/2 cups water for 4-5 whistles. Mash well and keep aside.
Heat oil in a pan & temper with mustard seeds & dry red chilies. After it stops spluttering, add the garlic, urad dal, asafoetida & curry leaves. Saute for a few seconds.
Add coriander powder, cumin powder & red chilli powder. Give it a stir.
Add the boiled dal, tamarind & salt. Simmer on a low flame for 2-3 minutes.
When done, switch off the flame and add coriander leaves.
Serve with hot steamed rice.
