Add dal to a pot or pressure cooker and rinse them very well with lots of water. Rub the lentils well with your hand while you rinse. Drain completely.
Pour water and pressure cook the dal on a medium heat for 3 to 4 whistles. To cook in instant pot, pressure cook on high for 10 minutes. To cook in pot check my notes below.
When the pressure drops naturally, open the lid. Dal should be soft cooked.
Lightly mash keeping some of the dal intact. Add more water only if required to bring to consistency.
While the lentils cook, to a medium pan pour oil and heat it. Add cumin seeds to the hot oil.
They will begin to splutter, then add ginger garlic and saute on a low heat until fragrant.
Add onions and green chilies. Fry them until slightly golden.
Reduce the heat. Add red chilli powder, turmeric and garam masala. Give a quick stir.
Stir in the tomatoes along with salt. Saute until the tomatoes become soft. The mixture begins to smell good at this stage.
Transfer this to the cooked dal and simmer for about 6 to 7 minutes. Taste test and add more salt at this stage. Then add kasuri methi and give the boiling dal a good stir. Add coriander leaves and turn off the heat.
Place a tall steel cup in the center of the pot. With a tong hold a wood coal over direct fire like a candle or lighter until a portion of it becomes red and hot. This will take about 2 minutes.
Place this gently into the cup and pour ½ teaspoon ghee directly over the hot coal. It will begin to release smoke. Quickly cover the pot and let the dal smoke for 3 to 4 minutes.
Transfer the hot cooked lentils to a serving bowl. Pour 2 tbsps ghee to a small pan & heat it on a medium heat.
Add cumin seeds and let them fry on a low heat until aromatic.
Next add red chilies and give a good stir. Add garlic and fry until light and aromatic. Do not brown.
Stir in asafoetida and red chili powder. Quickly remove from heat and pour the tadka over the dal.
Garnish dal tadka with coriander leaves. Squeeze some lemon juice over the dal while serving. Serve with Basmati rice, roti, paratha, naan, jeera rice or ghee rice.