In Cajun cooking, the combination of onion, celery, and bell pepper is called the holy trinity. These three vegetables are commonly diced and sautéed as the aromatic foundation for dishes such as gumbo, jambalaya, and crawfish étouffée.
The holy trinity is closely related to mirepoix, the classic French mixture of onion, carrot, and celery. Louisiana cooks commonly use bell pepper in place of carrot because bell peppers grew well in the region and were readily available. The substitution became a defining feature of Cajun and Louisiana cooking.
Garlic is frequently added to the mixture, but it is not one of the three core ingredients. Some cooks jokingly call garlic “the pope,” extending the religious naming theme. The term “holy trinity” became especially popular in print during the late 20th century, although the underlying cooking practice is older.
Mirepoix, bouquet garni, and sofrito are related culinary concepts, but they are not the standard Cajun name for this three-vegetable base.