Grind the tomatoes and puree them.
Take 1 cup of thin tamarind extract from a small gooseberry sized tamarind.
Add the tomato puree and tamarind water to an eeya chombu.
You can make it in a kadai too.
Add rasam powder, salt, asafoetida, turmeric powder and ½ cup of water.
Mix well and let this boil for 7-8 minutes in low flame.
Dilute the toor dal with 1 and ½ cup of water.
Add this to the eeya chombu or pan.
Let this froth up.
Do not allow this to boil after adding the toor dal water.
Once it froths up switch off the flame.
Add coriander leaves and curry leaves.
Add the freshly ground pepper powder.
Temper mustard seeds and cumin seeds in ghee.
Transfer it to the rasam.
Cover it and keep it for 5 minutes.
Serve with rice any poriyal or curry of your choice.