The Holy Trinity of Cajun Cooking

Onion, Celery, Bell Peppers — the Essential Trio

Making Gumbo With Cajun
Making Gumbo With Cajun "Holy Trinity" Mirepoix. Diana Rattray

The Holy Trinity

The holy trinity of Cajun cooking is made up of onion, celery, and bell pepper. This combination is the base of most savory dishes, more often than not added to roux as the beginning of stew, soup, sauce, jambalaya, sauce piquant ​or almost any other Cajun main dish.

A Sign of Importance and Respect

The importance of these three vegetables is indicated by the reference to the “holy trinity.” The mostly Catholic French Cajuns’ mean this allusion as a sign of the respect due to the place of onion, celery, and bell pepper in Cajun cookery.

Garlic is sometimes added to the trinity, and green onions and parsley are generally sprinkled on top of a finished dish.

Seasoning Vegetables

With these five vegetables, one has the makings of almost any savory Cajun entrée. Other seasonings include pepper—often black, white, and cayenne—bay leaves, and dried green herbs such as thyme, basil, and oregano. The trinity vegetables are known as “seasoning vegetables,” meaning that they break down during the long, slow cooking process and season the rest of the ingredients. They are not intended to be the vegetable component of a meal.


A typical “trinity” includes 2 cups chopped onion, 1 ½ cups chopped celery, and 1 ¼ cups chopped green bell pepper. In terms of how much to buy for this proportion, this amount is roughly equal to 2 medium onions, 2 stalks celery, and 1 large green pepper. The vegetables are usually cooked in oil, to which flour is then added before proceeding with the recipe.

The Trinity and Roux 

Perhaps the most common usage is to add the trinity to a roux that has been cooked to the desired color. See Roux, Oven Roux Recipe, Traditional Roux Recipe (Blonde), Microwave Roux Recipe.

Trinities in Other Cuisines

Even when a Cajun is cooking a dish that is not typically Cajun, such as spaghetti sauce, they generally use onion, celery and bell pepper.

Using a combination of three major ingredients in any cuisine is not particular to Cajun cooking: Mexican cuisine uses rice, beans, and chilies; the Greeks uses olive oil, lemon juice, and garlic; Italian cuisines would be lost without tomatoes, garlic, and basil; and Chinese cookery often contains onions, soy sauce, and rice.

If you do a lot of Cajun cooking each week, you might want to chop up a large batch of onion, celery and bell pepper to use as the base of almost any savory dish you choose to cook.

The Trinity in the Pantry

And speaking of chopping up, do just that—chop the vegetables. Cajuns don’t worry about or specify mincing, dicing, finely chopping, or coarsely chopping. They just chop the vegetables and put them in a pot with other common ingredients…yet, they continue to end up with some of the best tasting dishes in the world! So keep onions, celery, bell pepper, green onions, parsley, and garlic in your refrigerator or pantry and you’ll never be without the makings of a fabulous Cajun meal!