Wash the dal and add chopped tomato, green chilli,turmeric powder, salt and 2.5 cups water. Pressure cook till it's done (refer notes). Once the pressure releases open the cooker and whisk the dal till it becomes smooth.
In a small pan, heat ghee. Add cumin. Once it splutters, add crushed garlic and fry till it becomes brown. Add chopped onion and cook till it becomes golden brown. Add this and the chopped coriander leaves to the dal. Mix well. Sprinkle Amchur powder (if using).
Serve hot with rice or roti.
Notes
Pressure cooking dal - Since I prefer the dal to be mashed up, I cook it for 8-10 whistles on medium - high flame. Switch off the gas. Let the pressure drop naturally, around 10-15 mins. Keep in mind that dal tends to thicken as it rests, so adjust the qty of water accordingly. While reheating, add more water and reheat. Though I strongly recommend using ghee for this recipe, you can also use oil instead of ghee for tempering. If you are using oil add a tsp of ghee in the end. Though amchur powder gives a nice tang to the dish, you can also make this without it.