Wash the lentils well and add 2 cups of water to 1 cup of lentil and pressure cook for 6-8 whistles or till the lentils cook, mashed well.
Heat 1 Tbsp oil and add the mustard seeds and red chilli. When the mustard seeds crackle, add the cumin seeds and allow them to fry for 30 seconds.
Add the sliced onions, asafoetida powder, turmeric powder, curry leaves, green chillies, ginger garlic paste, tomato, tamarind Water, chilli powder and salt.
Once the above ingredients starts to boil, add 4 cups of water and cook for 20 minutes.
Add the cooked lentils, sugar and clarified butter, then cook it for 15 more minutes.
Garnish with coriander leaves.