1.Wash dal in few changes of water until water runs clear then leave to soak in cold water for about an hour. Drain Dal and keep aside.
2. Heat oil in a heavy based saucepan. Add the onions, ginger and garlic. Stirring frequently, fry for a few minutes until the mixture turns to a pale golden color. Add 3-4 tablespoon of water if the mixture sticks to the bottom of the pan.
3. Add chili powder, turmeric, salt and coriander powder and about 5 tablespoons of water to prevent the spices from burning. Stirring frequently, fry the mixture for about 5 minutes to a golden color.
4. Add the tomatoes. Still stirring frequently, fry the onion mixture for about 10 minutes until the tomatoes are reduced to a pulp. Add a little water, if necessary, to prevent the mixture from sticking to the bottom of the pan. Keep frying until the oil begins to separate.
5. Add the drained dal and water. Mix well, reduce the heat, cover and allow to cook for about 30 minutes or until dal is tender and all the moisture had dried up.
6.Add garam masala, coriander leave and green chilies.