Dry roast thuvar dhall and pepper without oil for 1 minute. Soak this in water along with red chilli & cumin seeds after 10 min . Wet grind this nicely. Boil Tamarind water, salt, turmeric, and add the above mixture, and let it boil for a few minutes until the flavour comes out. Fry 1/4 t.spoon cumin seeds, curry leaves and 1 red chilli in ghee and add this to the rasam.