Tender lentils slow-simmered with warming turmeric, finished with a sizzling tarka of golden ghee, roasted cumin, and fresh coriander.
Coarsely crush the peppercorns, cumin seeds and garlic cloves with a mortar and pestle.
Boil the tomatoes with tamarind pulp, water and salt for 10 minutes until the tomatoes break down.
Add the crushed masala and simmer 5 more minutes until frothy; do not over-boil.
Heat ghee, pop the mustard seeds, and pour over the rasam.
Rest 5 minutes and serve hot as a soup or with rice.