Tender lentils slow-simmered with warming turmeric, finished with a sizzling tarka of golden ghee, roasted cumin, and fresh coriander.
Stir the tamarind pulp and mashed tomatoes into 2 cups water with salt.
Coarsely crush the coriander seeds, cumin seeds, and peppercorns.
Combine everything in a pot with the asafoetida; boil 10 minutes until frothy and the raw tamarind smell is gone.
Heat the ghee, pop the mustard seeds and curry leaves, and pour into the rasam; switch off before it boils hard.
Serve over steamed rice or drink as a hot soup.