Pour idli batter into greased idli moulds and steam for 10-12 minutes.
Boil yellow lentils with turmeric powder and water until soft.
In a separate pot, cook drumstick pieces and chopped tomato with tamarind paste, sambar powder, and salt.
Combine cooked lentils with the vegetable stew and simmer for 5 minutes.
Temper mustard seeds, curry leaves, asafoetida, and dry red chili in hot oil and pour into sambar.
Serve hot idlis immersed in steaming sambar.