Sweat

To sweat an ingredient, usually vegetables, is to cook it gently in a small amount of fat over low heat until it softens and releases moisture, without browning. The term comes from French cooking (suer, "to sweat") and describes the standard first step for building an aromatic base - onions, celery, carrots, garlic, shallots, mushrooms - for soups, stews, braises, and sauces, as in a French mirepoix, Italian soffritto, or Cajun/Creole trinity. It differs from sautéing, which uses higher heat specifically to brown and caramelize food; sweating stays below the point of browning. The technique is also used to bloom ground spices or curry paste, releasing their aromatic oils before other ingredients are added.