Pressure cook: Add rinsed toor dal, sliced onions, chopped tomatoes, diced beetroot, turmeric powder, and water to the pressure cooker. Stir well, cover, and pressure cook over medium heat for 4-5 whistles or until the toor dal is cooked well. Turn off the heat and allow the pressure to release naturally.
Season: once the pressure is released, gently stir the cooked ingredients and turn on the heat again and set it to low. Adjust consistency by adding water if necessary. Then, stir in the salt and sambar powder, ensuring there are no lumps. Alternatively, you can mix the sambar powder in about 50 ml of water until its lump-free, then add the liquid to the cooked ingredients. Allow the sambar to boil. Taste: Taste for salt and seasoning, and adjust if necessary.Turn off the heat. Temper spices: Heat oil in a small pan on medium heat. Add mustard and cumin seeds and allow them to pop and sizzle. Then add the curry leaves and split red chilies, and allow the curry leaves to splutter. Turn off the heat.
Pour tempering over sambar: carefully pour the hot tempering over sambar.
Garnish: garnish with fresh chopped coriander leaves and give the sambar a gentle mix.
Serve: Serve delicious beetroot sambar with brown rice, pickles, and vegetable stir-fry. Enjoy!