The French term, mirepoix (pronounced “meer pwah”) is a group of aromatics that are used to season and flavor sauces, stocks, soups, and other foods. Mirepoix is also referred to as the “Holy Trinity” by many chefs around the world and it consists of finely diced carrots, onions, and celery that are sautéed in butter.
Typically the ratio for a mirepoix is 2 parts onion to 1 part celery and 1 part carrot according to weight. (Example: 1 pound of mirepoix would be 8 oz of onion, 4 oz of celery, and 4 oz of carrot) Since a mirepoix does not have to be exact down to the last ounce it can also be measured by volume to make it easier for the home cook. (Example: 2 cups onions, 1 cup celery, 1 cup carrot)
To make a mirepoix, brown the onions and carrots together over medium heat until nice and brown, then add in the celery and cook until soft.