Onion, Celery, and Carrot: The French Name

In French cooking, the classic combination of onion, celery, and carrot is called mirepoix (pronounced meer-PWAH). These diced vegetables are gently cooked in fat to build a savory base for soups, stews, sauces, and braises; the traditional French ratio uses twice as much onion as carrot and celery.

Ingredients

2 cups (300 g) yellow onion, peeled and cut into small dice
1 cup (125 g) carrot, peeled and cut into small dice
1 cup (100 g) celery, trimmed and cut into small dice
2 tablespoons (30 ml) olive oil or 2 tablespoons (28 g) unsalted butter
¼ teaspoon fine salt (about 1.5 g), plus more to taste
2 tablespoons (30 ml) water, as needed to prevent sticking

Instructions

Prepare the vegetables. Peel and finely dice the onion and carrot, then dice the celery to a similar size. Aim for pieces about ¼ inch (6 mm) across so they soften evenly. You should have roughly 2 cups onion, 1 cup carrot, and 1 cup celery; exact volume can vary slightly with the shape of the vegetables.
Warm the fat. Set a medium, heavy-bottomed skillet or saucepan over medium-low heat. Add the olive oil or butter. When the butter has melted or the oil shimmers lightly, add the diced vegetables and salt.
Cook gently. Stir to coat the vegetables, then cook uncovered for 12–15 minutes, stirring every couple of minutes. Keep the heat low enough that the vegetables soften without browning. If the pan begins to look dry or the onion catches, add a tablespoon of water and lower the heat.
Check the texture. The mirepoix is ready when the onion is translucent and the carrot and celery are tender but still hold their shape. Taste and adjust the salt. Use it right away as a recipe base, or cool it promptly for storage.

Tips

Keep the pieces even. Consistent dicing helps the vegetables cook at the same rate. Smaller pieces are useful for a smooth soup or sauce; slightly larger dice work well in a rustic stew.
Do not rush the heat. Mirepoix is usually softened rather than browned. High heat can scorch the onion before the carrot and celery become tender, and a browned mixture will give a dish a sweeter, deeper flavor than a gently cooked base.
Use the classic ratio as a guide. The familiar French proportion is 2 parts onion to 1 part carrot and 1 part celery by volume. A little variation is fine, especially when using up vegetables.
Choose your fat for the dish. Olive oil is convenient and dairy-free; butter gives the base a rounder, richer taste. For a vegan version, use olive oil or another neutral plant oil.

Serving Suggestions

Mirepoix is primarily a cooking foundation rather than a finished side dish. Stir it into lentil, bean, chicken, or vegetable soup; use it at the beginning of a stew or braise; or add it to a tomato sauce, gravy, or savory pie filling. It also brings a gentle aromatic base to rice, barley, and other grain dishes. Add broth, tomatoes, herbs, or the main ingredients after the vegetables have softened, following the cooking time required by that dish.

For a simple vegetable side, cook the mixture until fully tender, season with black pepper and chopped parsley, and serve warm. That is a practical variation rather than the usual role of mirepoix, which is generally incorporated into a larger recipe.

Variations

White mirepoix: In some French preparations, cooks replace the carrot with leek or use pale vegetables such as celery root and parsnip. The result is milder and lighter in color, useful when a dish should not take on the orange tint of carrot. Leek has a gentle onion flavor; parsnip is sweeter.

Oil-free: Soften the vegetables in a covered pan with a few tablespoons of water or broth, stirring regularly and adding more liquid in small amounts when needed. The vegetables will steam rather than develop the richness that fat provides.

Herb additions: Add a bay leaf or a few thyme sprigs to the dish that will use the mirepoix, rather than necessarily cooking them with the diced vegetables. This lets the aromatics infuse the soup, sauce, or braise and makes them easy to remove.

Different cuisines, different names: Italian soffritto often includes onion, carrot, and celery, while Cajun and Louisiana cooking uses the related “holy trinity” of onion, celery, and green bell pepper. These are useful alternatives, but they are not identical to classic French mirepoix.

Storage and Reheating

Let cooked mirepoix cool briefly, then refrigerate it in a clean, covered container within 2 hours of cooking. It keeps for 3–4 days in the refrigerator. Reheat only the portion you need in a skillet over medium-low heat, stirring until steaming hot; if you are adding it to a larger dish, make sure the finished dish is thoroughly reheated. Leftovers that are reheated should reach 165°F (74°C).

For longer storage, freeze the cooled vegetables in a freezer-safe container or flat in a labeled freezer bag for up to 3 months for best quality. Thaw in the refrigerator or add frozen portions directly to a soup or stew. Do not leave cooked vegetables at room temperature for more than 2 hours.

Frequently Asked Questions

What is the French name for onion, celery, and carrot?
The combination is called mirepoix. The word usually refers both to the diced vegetable mixture and to the gently cooked aromatic base made from it.

What is the traditional mirepoix ratio?
A common French guideline is two parts onion to one part carrot and one part celery by volume. It is a useful starting point, not a rule that must be followed precisely in every recipe.

Do I have to cook mirepoix before adding it to soup?
Most recipes soften it first in oil or butter so its flavors blend into the dish. Some slow-cooker recipes may add raw diced vegetables directly, but follow the specific recipe because the texture and flavor will differ.

Can I make mirepoix without celery?
Yes. Use more onion and carrot, or substitute a modest amount of leek or celery root. The flavor will not be exactly the same: celery contributes a fresh, slightly savory note that the alternatives change or soften.

Is mirepoix the same as soffritto?
They are closely related vegetable bases, and many versions of Italian soffritto use onion, carrot, and celery. Usage varies by region and recipe, and soffritto may be cooked differently or include other ingredients such as garlic.

Can I chop the vegetables ahead?
Yes. Store the raw diced vegetables in a covered container in the refrigerator and use them within about 2 days for best quality. Keep them chilled and cook them as directed; once cooked, follow the separate 3–4 day storage guidance above.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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