Soak the tamarind for 15 minutes in 1/2 cup of warm water. Now drain the water in a separate bowl by removing the pulp.

Heat a pan and add oil. When its warm add mustard seeds and let it crackle.

Now add the chopped onions, slit green chill, curry leaves and sauté for a minute.

When onions turn translucent, add the tomatoes and sauté well for few minutes. Mash the tomatoes with the back of the ladle lightly.

Add salt, turmeric powder sambar powder, tamarind water. Mix it well and add 1/2 cup of more water. Close the pan with a lid. Lower the flame and let it cook for few minutes.

Transfer the content in a bowl and serve it hot with Idli/Dosa/Pongal.