Soak tamarind in 1 cup of warm water for 15 minutes. Extract the juice by removing the pulp and seeds.
In a sauce pan, add tamarind water and chopped tomatoes.
Add pepper rasam powder, turmeric powder, jaggery, salt and 2 cups of water. Mix it well, lower flame and let it cook for few minutes minutes.
Add some fresh coriander leaves, mix well and remove from flame.
In a small frying pan, add ghee and mustard seeds. When mustard seeds crackle, add asafoetida and curry leaves.
Add this tempering to rasam and serve.