Tender lentils slow-simmered with warming turmeric, finished with a sizzling tarka of golden ghee, roasted cumin, and fresh coriander.
Soak the tamarind in 2 cups warm water for 15 minutes, squeeze, and strain the extract.
Simmer the tomatoes with 1 cup water and the salt until soft, then crush them.
Coarsely crush the peppercorns, cumin seeds, and garlic.
Add the tamarind extract and the crushed masala and simmer 8 minutes until the raw smell is gone; do not let it boil hard.
Melt the ghee, pop the mustard seeds and curry leaves, and pour over the rasam.
Serve hot with steamed rice.