Heat oil, add mustard seeds, when it splutters, add fenugreek seeds, red chili, asafoetida, curry leaves. Saute well.
Now add tamarind extract and bring to a boil.
When the tamarind cooks for 5 to 7 mins on high, add the cooked bitter gourd and chana. Mix everything well.
Add the cooked toor dal, ground paste along with half a cup of water.
Cook for 3 to 4 mins on low flame until everything gets blended well.
Check for seasoning. Since salt is added at various stages, you will have to check if its enough.
Garnish with coriander leaves and serve hot with rice.