First soak the Tamarind for sometime.Grind the dried can berries with the tamarind juice. Take a pan and add 2 tablespoon of oil in it. Add mustard seeds, Cumin seeds, curryleaves and hing. Add sliced green chillies. Add the mixture from the belender. Now add Jeera powder, cumin powder, pepper powder along with salt and Red Chilly powder. Add water as required. Now let it boil for 15 min. Serve it with hot rice and dal. It really tastes good. I tried this when I did not have tomatoes at home and wanted to make rasam. Its just my experiment but it really came out well. (Optionally we can add ginger garlic paste.)