Pressure cook the lentils along with the onion, chillies and turmeric till done.
Grind the ingredients under "for grinding" till smooth and set aside.
In a chatti, heat oil. Splutter mustard seeds. Fry the curry leaves and shallots till cooked.
Add in the cooked dal, the ground paste, tomato, salt and water as required. Simmer for around 5 minutes and switch off.
Serve hot along with rice and sides.