Wash the lentils well and soak them in water with the curry leaves and red chillies for ½ hour to 1 hour. Grind to a coarse paste (just pulse one or two times) with the salt and asafoetida. Take out almost all of it leaving behind maybe ¼ of it in the food processor. Grind it to a very smooth paste and keep aside. Make small key lime sized balls of the coarse mixture and keep aside.

Squeeze out the pulp from the tamarind and keep adding more water and squeezing the pulp from the tamarind till when you add water next its almost pale. Repeat this for maybe about 4-5 times.

Keep a pot over medium heat and pour the tamarind pulp in it. Add a little water if it is too thick. Bring it to a boil and add the smooth lentil paste to this. Add salt and the sambar powder too. Let it boil for a while and add the lentil balls to it very slowly. Make sure they dont break. Let it cook for about 15-20 mins without stirring.

Heat the oil for tempering and add the rest of the ingredients. Once the mustard seeds splutter and the curry leaves and red chillies have toasted a little, add them to the gravy and mix well. Enjoy with some rice, a side of vegetables and maybe some yogurt too :)