Mirepoix is the French name for a combination of onions, carrots and celery (either common Pascal celery or celeriac). Mirepoix, either raw, roasted or sautéed with butter, is the flavor base for a wide number of dishes, such as soups, stews and sauces.

These three ingredients are commonly referred to as aromatics. Similar combinations, both in and out of the French culinary repertoire, may include

these, as well as leeks, parsnips, garlic, tomatoes, shallots, mushrooms, bell peppers, chiles, and ginger. For the combination mirepoix au gras, or a Matignon, ham and/or pork belly are used as additional ingredients.

They may be used in various combinations, as dictated by the cuisine and the dish itself.

Traditionally, the ratio for mirepoix is 2:1:1 of onions, celery, and carrots. The ratio for bones to mirepoix for stock is 10:1. When making a white stock, or fond blanc, parsnips are used instead of carrots to maintain the pale color.

"Mirepoix"
Mirepoix derives its name, as many other elements of French cuisine do, from the patron of the chef who established it, in this case one of the house of Lévis, seigneurs of Mirepoix since the eleventh century, a famous name in Languedoc. The particular member of the house of Lévis whose chef is credited by the Dictionnaire de l'Académie française with giving a name to an old technique is Charles-Pierre-Gaston François de Lévis, duc de Lévis-Mirepoix (1699-1757), maréchal de France and ambassador of Louis XV.