To prepare beetroot sambar, we need to first cook the beets and lentils. Pressure cook the dal with a pinch of turmeric. If you don't have a pressure cooker, then soak dal for 30 minutes and boil with 3 cups of water for 30-40 minutes until mushy.
Pressure cook the beetroot. If you are using a pressure cooker, use the separators and cook dal in one compartment and beets in the other to save time. Cooking time is similar for both tur dal and beetroot.
Tug off the skins from the cooked beetroot and cut into thick slices and dice.
Heat the oil in a pot. Add the mustard seeds, fenugreek seeds and curry leaves. Once the mustard seeds pop, add a pinch of asafoetida and give it a quick stir.
Add the cooked chopped beets, stir for around for 2 minutes. Add the tamarind extract to this and bring to a simmer.
Slake the sambar powder in 1/4 cup water and add it to the pot. Bring to a simmer.
Put the cooked dal, salt and boil for 2 minutes.
Serve with steamed rice and ghee.