Pour idli batter into greased moulds and steam for 10-12 minutes.
Pressure cook yellow lentils with water and salt until soft.
Cook drumstick pieces and chopped tomato in water with tamarind paste, sambar powder, and salt.
Combine cooked lentils into the vegetable broth and simmer for 5 minutes.
Temper mustard seeds and curry leaves in hot oil, pour into sambar, and serve hot over idlis.