Take black lentils in a large bowl and wash well. Cover with water and let stand overnight.

Drain and wash lentils. Place sabut urad dal in a pressure cooker and add 3 cups of water, one sliced onion, 2 slit green chillies, salt and hing.

Pressure cook for 6-7 whistles on medium-high flame or till lentils are very tender. Drain the cooked whole black urad dal; reserve the cooking water.

Heat oil in a large pan over medium-high heat. Add the remaining sliced onions and fry till they start to brown.

Add the ginger juliennes and minced garlic to the pan. Fry for a minute.

Add the chopped tomatoes and cook for 4-5 minutes, till softened.

Add the spices – salt, chilli powder, cumin powder and coriander powder. Fry for 1-2 minutes till all the ingredients are well incorporated and the mixture is fragrant.

Add the tender black gram lentils to the pan and mix well. Add the reserved cooking water and cook covered for about 10 minutes, till you get a thick gravy-like consistency.

Stir in heavy cream and simmer for 1-2 minutes, until well combined. (You can substitute cream with milk).

Remove from heat and add a small knob of butter. Set aside the black gram dal.

Heat ghee in a small kadai. Add cumin seeds and sauté till they stop popping. Carefully pour the tadka over the cooked lentils and mix to combine. Garnish with freshly chopped coriander leaves.