The ingredient that is never the point of the dish
A great many Indian gravies contain a ground paste of something oily that no one tastes as a distinct flavour. Cashew in the north, poppy seed across a wide band, melon and cucumber seeds in the west, groundnut in the Deccan, sesame in parts of the south. They are rarely announced in the name of the dish and they are doing a large share of the structural work in it.
They’re also usually the most expensive thing in the pot, which is why the choice tracks what grows locally and what a household could afford, and why the same dish moves between them as you cross a few hundred kilometres. The paste’s identity is a matter of geography rather than of the recipe’s ambition.
Three contributions from one spoonful
A nut or oilseed ground fine releases oil, which enters the sauce as fine droplets and adds to the fat already there, contributing body and mouthfeel and helping the emulsion hold. It releases protein, which is surface-active and helps stabilise that emulsion rather than merely adding to it. And the ground solids themselves remain suspended as fine particles that make the liquid thicker simply by getting in the way.
That last mechanism is often missed. A suspension of very fine particles is thicker than the liquid it sits in, whatever the particles are made of, and it also scatters light, which is why a nut-thickened gravy reads as opaque and pale rather than translucent.
Some of them bring starch as well. Cashew has a meaningful amount, and it swells and gels when the sauce simmers, which is why a cashew gravy continues to thicken after the paste goes in while a sesame one largely does not.
Grinding fineness matters more than quantity
The same weight of nut ground coarse and ground fine gives two different sauces. Coarse particles feel gritty, settle out on standing and release much less of their oil, because the oil is still locked inside intact cell fragments. Fine grinding ruptures those cells and puts the oil into the mixture where it can be emulsified.
Roasting before grinding is a separate decision that changes the flavour rather than the mechanics. A raw paste disappears into a sauce and contributes body without announcing itself, which is what most gravies want from it; a roasted one brings a pronounced nutty character that becomes part of the dish. Several regional preparations specify one or the other quite firmly, and the two are not casually swapped.
Soaking first is what makes fine grinding possible for a hard nut, and it also softens the tissue so the machine does less work and generates less heat. That is worth caring about, since heat during grinding drives off aroma and can push an oily paste towards separating into a greasy mass rather than a smooth one.
Each one behaves differently in the pan
Poppy seed carries a good deal of oil and very little starch, and it gives a sauce that is smooth and slightly grainy in a way people recognise as characteristic rather than as a fault. Melon and cucumber seeds do something similar with a milder flavour. Groundnut brings more protein and a pronounced roasted taste that is meant to be noticed, which is why it appears in dishes built around it rather than in ones where it should disappear.
Almonds are the outlier in the group, being firmer, lower in oil than cashew and carrying a skin that has to come off if the sauce is not to be flecked. They give a paler, slightly drier body than cashew does and are used where that is wanted. Blanching and slipping the skins is tedious enough that most kitchens reach for something else unless the dish specifically calls for them.
Sesame is the strongest-flavoured of the group and behaves half like a thickener and half like a spice. Coconut, which does much the same job in the south, is a separate case with its own rules. And all of them tolerate acid and long cooking better than dairy does, which is a large part of why they were used in the first place.
They go rancid, and the paste goes faster
Everything in this group is high in oil, and oil in contact with air, warmth and light gradually oxidises into compounds that taste stale and slightly of paint. A whole nut is protected by its own structure and by whatever skin it has; a ground paste has enormous surface area and deteriorates in a fraction of the time.
This is the argument for buying whole and grinding as needed, and for keeping the reserve somewhere cool and dark rather than in a jar above the stove. Poppy and sesame seeds are particularly prone to it because of the kinds of oil they contain, and a batch that smells sharp or bitter in the bag will not improve in the pot. Roasting fresh before grinding masks a little staleness and does not remove it.
Common questions
Can I use one of these in place of cream?
Often yes, and in a great many dishes the nut paste is the older answer and the cream is the newer one. The result is not identical: cream brings dairy flavour and a specific richness, while a nut paste brings body and a faint sweetness and holds up better to acid and to reheating.
Why did my cashew gravy turn grainy?
Usually because the grind was too coarse, or because the sauce was boiled hard after the paste went in and the emulsion broke. Grinding finer with a little liquid, and keeping the pot below a rolling boil once the paste is in, deals with both. A splash of water and vigorous stirring will sometimes bring a broken one back.
Is there a cheaper substitute that behaves the same way?
Melon seeds and roasted gram flour are both used exactly this way in domestic kitchens, and either can carry a gravy respectably. Neither tastes like cashew, and roasted gram brings a pronounced flavour of its own. They are honest alternatives rather than imitations, and the dishes built around them are their own thing.
Consumer editor, Wah Taste
Nadia has written about everyday cooking, street food, spice & pantry for most of the last decade and is unreasonably interested in the detail nobody else checks.
