Wash rinse and soak the beans in a lot of water overnight.
Drain water and pressure cook for 3 – 4 whistles with fresh water. Drain and allow it to cool
Soak the tamarind in water and squeeze well to extract the juice.
Grind or mash the cooked beans and set aside.
Heat a teaspoon of oil in a vessel. Add the chopped onion and chopped tomato and fry for a couple of minutes.
Then add a little water and cover with a lid. Let it cook until soft.
When the onion and tomatoes are cooked, add the cooked beans paste, tamarind extract, salt, red chilli powder, jaggery, sambar powder and water (adjust to desired consistency) to the cooked onions. Allow the sambar to boil and thicken.
Now add the coconut powder and cook for another 2 minutes.
Remove from the heat and set aside.
Heat oil in a pan for seasoning. Add the mustard seeds and cumin seeds and let them splutter.
Now add the red chillies, curry leaves and hing and stir for a couple of seconds.
Pour the tempered ingredients over the prepared sambar and combine well. Serve hot with rice, idli or pongal.