Tangy South Indian Tomato Rasam

Rasam is the everyday soup of many South Indian kitchens. It is thin, sour and sharp, and it often shows up after a heavy meal or on a day when nobody wants much else. My mother never made it from a packet of powder. She dry roasted her own spices, and this recipe follows that habit. Toasting the chana dal, coriander seeds, peppercorns and cumin in a small pan for a few minutes wakes up their oils in a way that raw spices never do. Let them cool a little before you grind them, or the mixer will steam and the powder will turn gummy.

A food fact worth knowing: tomatoes are mostly water, and they give rasam its body without any cream or flour. The sourness comes from tamarind, which has been used in Indian cooking for centuries and adds a fruity tang that lasts. The jaggery in the recipe is there to round off the sour edge, not to make the soup sweet. Taste as you go. If your tomatoes are very ripe, you may need a little less tamarind.

Tip: the tempering matters as much as the spices. Once the ghee is hot, the cumin and curry leaves should sizzle right away. Add the garlic and the round red chillies just before the tomatoes so the garlic does not scorch. Keep the flame at medium so the curry leaves crisp without going black.

Rasam keeps well for two days in the fridge. Reheat it gently in a small pot and do not let it boil hard, since a rolling boil can dull the fresh aroma. It also freezes, though the coriander leaves are best added fresh after reheating. Leftover rasam makes a lovely base for a quick stir-fried vegetable or a spoonful of cooked rice mashed into it.

For serving, a simple plate of steamed rice is the classic partner, and a little plain yogurt on the side cools the heat. If you want something more filling, try Golden Chickpea Tikki with Mint alongside, or a Spinach and Toovar Dal with Whole Spices for a more substantial meal. A glass of Chilled Cumin Chaas Drink makes a cool contrast to the warm, sour bowl.