Cook toor dal with 1 cup of water until soft.

Whisk the cooked dal until smooth and set aside.

Puree the roughly chopped tomatoes in a blender and set aside.

Heat ghee in a pressure cooker on medium heat.

Add mustard seeds, cumin seeds, garlic, and curry leaves to the ghee. Let mustard seeds crackle.

Pour in the tomato puree, tamarind water, coriander powder, turmeric powder, cumin powder, asafoetida, pepper, and chili powder.

Stir all the masalas together and pressure cook for one whistle. Turn off the heat.

Once the pressure has released, open the cooker and add the cooked toor dal.

Adjust the consistency of the rasam with 1-1/2 to 2 cups of water.

Check and adjust salt and spices to taste.

Bring the rasam to a brisk boil, then simmer for 10 minutes on low heat until frothing.

Turn off the heat.

Garnish with freshly chopped coriander leaves.

Serve hot with rice and ghee, accompanied by a vegetable curry.