Pressure cook the dal and keep aside.
Cut drumstick into 4-5 pieces. Peel and chop carrot and potato into large chunks.
Peel and cut onion into thick slices.
In a small pressure cooker or pan, heat coconut oil. Add mustard seeds, fenugreek. Stir for few seconds.
Add all vegetables, turmeric, salt and 1/2 cup light tamarind extract (or 1 tsp turmeric paste whisked in 1/2 cup hot water).
If cooking them in a pan, cover and simmer until potato/carrot is cooked. In a pressure pan / cooker, close with the lid and pressure cook for one whistle.
Open, add in the sambar powder, asafoetida, mashed dal. Adjust salt as per taste. Bring to a simmer.
Heat the oil in a small pan. Add mustard seeds. Once it splutters, add the curry leaves and red chillies. Then add the sliced shallots and stir until golden brown.
Transfer this over the sambar and keep covered until ready to serve.
Serve with red rice and banana chips.