Why do recipes tell you to fry tomato paste first?

A tube or small tin of tomato paste is one of the most useful things in a kitchen, and one of the most misused. Stirred into a pot of liquid straight from the tube, it can taste sharp, flat and faintly metallic. Given a few minutes in hot oil first, it becomes something else entirely: rich, rounded and deeply savoury.

What tomato paste is

Wikipedia's tomato paste entry describes it as tomatoes cooked down for a long time to reduce their water, strained of skins and seeds, then cooked again into a thick concentrate used to give dishes an intense tomato flavour. In other words, it is tomato with most of the water gone. That concentration is the point, but it also means any raw, acidic edge is concentrated too.

Why frying helps

When you cook paste directly in hot fat, without much liquid around it, its surface can brown. Browning reactions are a big part of why cooked food tastes the way it does: Wikipedia's Maillard reaction entry describes the reaction as creating the compounds that give browned food its distinctive flavour, and notes that at higher temperatures caramelisation and then burning take over. In the pan, the practical result is simple: the paste loses its raw sharpness and gains a darker, sweeter, more savoury taste.

Stirred straight into stock or water, the paste can't brown, because the liquid keeps it too cool. It still adds colour and tomato flavour, just not that depth.

How to do it

1. Cook your onion, garlic or soffritto first, so the paste goes into a pan that already has flavour.
2. Push the vegetables to one side, add a little more oil if the pan looks dry, and put the paste in the clear space so it touches the hot surface.
3. Stir and spread it around with a wooden spoon, then mix it through the vegetables.
4. Keep it moving for a few minutes over a medium heat.

The cues it's done

• Colour: it shifts from bright, almost neon red to a deeper rusty or brick red.
• Texture: it loosens, looks glossier and starts to stick a little to the bottom of the pan.
• Smell: the sharp, raw tomato smell turns sweeter and rounder, closer to roasted tomatoes.

When it reaches that point, add your liquid: tinned tomatoes, wine, stock or water. Scrape the bottom as you go to lift the browned bits into the sauce; our page on deglazing explains why that layer is so valuable.

Don't go too far

There is a difference between dark and burnt. If the paste turns blackish, smells acrid or the fond on the pan base turns black rather than brown, it will make the dish bitter. Keep the heat moderate, keep stirring, and have your liquid ready before you start.

How much to use

Tomato paste is a seasoning, not a sauce base on its own.

• In a tomato sauce made from tins: a spoonful deepens colour and flavour, especially when the tomatoes taste a little thin. Our guide to a tomato sauce that tastes flat puts it in context.
• In soups, stews and bean dishes: a spoonful or two gives body and a gentle tomato note without turning everything into tomato soup.
• In vegetable stock: a small spoonful, fried with the vegetables, gives colour and savouriness.

Start small. You can always add more later, but too much paste can taste heavy and slightly bitter.

Not all pastes are equally strong

Pastes vary from brand to brand, and some labels tell you how concentrated they are. A thicker, darker paste needs less, and benefits even more from frying first. When you switch brands, start with a little less than usual and taste.