Mirepoix (pronounced "meer-pwah") is a fundamental element of classical cuisine; it's the key to flavor and aroma in so many dishes. While it can be seen as grunt work, chopping mirepoix is one of the few things a student of the culinary arts can be absolutely certain of.
There are only three things in a mirepoix: carrots, celery, and onions. When combined, these three simple ingredients, commonly referred to as "aromatics," come together to add flavor and aroma to stocks, sauces, soups, and other foods.
Cajun chefs use a variation on mirepoix which consists of three parts onions, two parts celery, and one part green bell pepper, and they take it so seriously they refer to it as "the holy trinity." Other variations, like the Spanish and Italian sofrito or the German suppengrün, utilize tomatoes, parsnips, leeks, celery root, fennel bulb, shallots, or garlic.
Traditional mirepoix consists of two parts onions, one part carrots, and one part celery, with the proportions determined by weight. Therefore, one pound (16 oz) of mirepoix would be made up of 8 ounces of onions, 4 ounces of carrots, and 4 ounces of celery.
If you're in culinary school or a stickler for the rules, then you'll want to break out the kitchen scale to get the ratio exact. But if you're cooking at home, you can feel free to eyeball it. Mirepoix isn't something that needs to be calibrated to the exact gram. You could even use volume measurements (like two cups onions and one cup each of carrots and celery) instead of weight, and it'll still work fine.
How to Use It
When you're making stock, the mirepoix is ultimately strained out, so you don't need to be particularly precise when chopping the vegetables. The pieces should be more or less uniform in size to allow for uniform cooking times.
The more finely mirepoix is chopped, the more quickly its flavor and aroma are released into stock. Since the brown stock is simmered longer than white stock, it's perfectly acceptable to cut the mirepoix into pieces an inch or two in size. For white stock, a 1/2-inch dice is probably best.
If you're using the mirepoix for other recipes, the recipe should say how fine to dice the veggies. Also, you may notice some recipes, like a slowly cooked beef stew, may call for carrots, celery, and onions, but won't refer to it as a mirepoix. Now that you know the term, you can look out for the three ingredients.
- Leeks can be used in place of some or all of the onions.
- If you want a colorless stock, you can make a "white mirepoix" by substituting parsnips, mushroom trimmings, or both, for the carrots, or just omitting the carrots altogether.