Salt as needed
Boil the tomatoes.. peel the skin and blend them into a purée.
Pressure cook dal and keep aside.
In a vessel add the purée tomato,tamarind paste,1/2 cup of water and to it add turmeric,salt,rasam powder and asafetida and allow it to boil for 5 to 7 mins.
Then to it add the cooked dal water,coriander leaves.
When the foam forms add the curry leaves and temper with mustard and cumin.
Serve hot with rice.. very juicy and tasty rasam..kids will love it.