Pressure cook the moong with tomato, onion, garlic, green chillies, curry leaves, turmeric powder and salt and three cups of water.
Cook till the pressure is released thrice.
Heat oil in a small pan and add cumin seeds. Once they begin to change colour, add asafoetida.
Remove from heat and add red chilli powder. Add this tempering to the dal.
Serve hot with chapattis.