Tender lentils slow-simmered with warming turmeric, finished with a sizzling tarka of golden ghee, roasted cumin, and fresh coriander.
Soak the tamarind in warm water, squeeze and strain to get the pulp.
Combine the pulp, water, rasam powder, turmeric, and salt and boil 10 minutes until the raw smell disappears.
Heat ghee and pop the mustard seeds, curry leaves, and dried red chilies.
Pour the tadka into the rasam.
Simmer 2 minutes more without boiling hard and serve hot as a soup.