Rasam

Why must rasam not boil once the dal is in?

Because hard boiling ruins both the taste and the look of it. The aromatic compounds in black pepper, cumin and curry leaf are volatile and a rolling boil drives them off, leaving something that tastes dull and flat rather than sharp. The dal also breaks down under sustained heat and turns the broth cloudy and thick, when the whole point of rasam is that it stays thin enough to drink. The correct end point is the moment a white froth rises up the sides, which happens well below a full boil. Take it off then, cover it, and let the residual heat finish the job.

What is the real difference between rasam and sambar?

Consistency and the job each one does. Sambar is thick, built on a full quantity of cooked toor dal and loaded with vegetables, and it is a dish in its own right. Rasam uses a couple of spoons of dal purely for body, carries no vegetables beyond tomato, and is deliberately thin enough to drink from a tumbler. The spicing differs too: sambar powder leans on coriander and fenugreek, rasam powder leans on black pepper and cumin. In a South Indian meal they are served in sequence, sambar rice first and rasam rice after, precisely because the second is lighter than the first.

Can rasam be made without dal?

Yes, and several traditional versions have none at all. Milagu rasam, the pepper rasam given to anyone with a cold, is tamarind, pepper, cumin and garlic with no dal and no tomato. Lemon rasam skips both the dal and the tamarind and uses lemon juice added off the heat. A rasam without dal is thinner and clearer and considerably sharper, which is exactly what it is for. Adding dal is a choice about body rather than a requirement, though it does contribute the small amount of protein the dish contains.

When does the rasam powder go in, and when does the pepper?

The rasam powder goes into the tamarind water at the start, because it contains whole ground spices that need time in liquid to open up and lose their raw edge. The freshly crushed pepper and cumin go in near the end, because their aroma is the thing you want to survive into the bowl, and ten minutes of simmering would waste it. This split is what separates a rasam that smells of something when it reaches the table from one that does not. Crush the pepper and cumin coarsely in a mortar rather than grinding them to powder, so they release slowly.

Why rasam earns its place beside a meal

It is one of the few things on an Indian table that adds flavour, warmth and a lot of liquid for almost no energy, which makes it genuinely useful when the rest of the meal is heavy. The warmth and the pepper make people eat more slowly. The traditional claim that it settles the stomach rests on cumin, pepper and asafoetida, all of which have long culinary use as digestives, though that is a reason to enjoy it rather than a treatment for anything. Following it with curd rice is the standard close to a South Indian meal and a sensible one. The interest in fermented and easily digested foods across this whole cuisine is covered in the gut health course.

Storing it and reheating it

Rasam keeps two days refrigerated and many people think the second day is better, since the tamarind and the spices settle into each other. Reheat it gently and stop before it simmers, for the same reason you stopped the first time. It separates in the fridge, with the dal sinking, so stir it thoroughly before warming. Do not freeze it; the texture goes grainy and the aroma is gone. Made fresh it takes under half an hour, which is less time than most people spend defrosting.