Pressure cook dal with 1/4 tsp. turmeric powder and when done, add 1 cup water, churn, set aside.
Boil tamarind in water, take out extract.
To tamarind water add tomato pieces, green chilles, curry leaves, 1/4 tsp turmeric powder, rasam powder and salt. Boil till the quantity is ruduced to less that half and the raw smell of tamarind is not there any more.
Add churned dal, jaggery and simmer for a while. When it is about to boil over, remove from fire.
Season ingredients in ghee, Add it to rasam along with chopped coriander leaves.