Sweat

To sweat is to cook chopped vegetables slowly in a little fat over low heat until they soften and release their juices, without letting them brown. Onions, shallots, leeks, celery, carrots, fennel and garlic are the usual ones. Sweating gives a soft, sweet, mellow base for soups, risotto, sauces and stews. It is the first step for mirepoix and soffritto.

How to do it

1. Chop the vegetables into small, even pieces.
2. Melt butter or warm oil in a heavy pan over low to medium-low heat.
3. Add the vegetables and a pinch of salt. The salt draws out moisture and helps them soften.
4. Stir to coat them in the fat.
5. Cook gently, stirring every minute or two. Onions usually take 8 to 12 minutes.
6. If they start to color, turn the heat down or add a tablespoon of water.
7. Some cooks lay a round of parchment or a lid on top to trap steam, which speeds softening.

How to tell it is done

The vegetables are soft and limp, and onions turn translucent, with no brown edges. They smell sweet, not toasted. When pressed with a spoon they give way easily.

Why it works

Low heat breaks down the vegetables' cell walls, so water and natural sugars escape. The water keeps the pan below browning temperature, so the vegetables stew gently in their own juices. The flavor ends up sweet and mild, without the deeper, roasted taste of caramelization or browning.

Common mistakes

• Heat that is too high. The vegetables brown before they soften, and that is a sauté, not a sweat.
• Not stirring. The bottom layer colors while the top stays raw.
• Adding garlic at the start. It burns easily. Add it in the last minute or two.
• Too little fat. Vegetables catch and brown on the pan.
• Rushing. Underdone onions taste sharp and stay crunchy in the finished dish.

In recipes

"Sweat the onions until soft but not colored" and "soften the onions without browning" both mean this. "Cook until translucent" is the same step described by how it looks.