Mirepoix

Mirepoix is a flavor base made from diced vegetables cooked—usually with butter, oil, or other fat—on a low heat for a long time, so that they soften but not brown, as further cooking, often with herbs, spices, and sometimes tomato purée, will color and caramelize them. It is a fundamental building block of French cuisine, and its aroma provides a foundation for many sauces, soups, stews, and braises.

The traditional mirepoix consists of onions, carrots, and celery, typically in a ratio of 2:1:1, respectively. The exact ratio and the vegetables used can vary depending on the regional cuisine and the specific dish being prepared. For instance, a "white mirepoix" or mirepoix au blanc omits the carrots, replacing them with parsnips or mushrooms to maintain a pale color. This is often used in light-colored sauces and broths where a dark color would be undesirable.

While mirepoix is most commonly associated with French cooking, similar flavor bases exist in other cuisines. The Italian soffritto, the Spanish sofrito, and the Cajun "holy trinity" of onions, celery, and bell peppers serve analogous purposes, providing a foundation of flavor for a wide range of dishes.

The purpose of mirepoix is to create depth of flavor and aroma, rather than contributing a strong, individual flavor of its own. The slow, gentle cooking allows the vegetables to release their sweetness and meld together, creating a harmonious base for the other ingredients in the dish.