What Is the Cajun Trinity?

The Cajun Trinity: Onions, celery and bell peppers

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If you've ever tried preparing a Cajun or Creole recipe, like gumbo, jambalaya or étouffée, you've probably noticed a trio of vegetables common to the ingredient lists of all three: onions, green bell peppers, and celery.

Together, these three ingredients are referred to in Cajun and Creole cuisine as the Cajun trinity, or sometimes the holy trinity, or simply the trinity. But what is the Cajun trinity, and why is it so important?

A Cajun Mirepoix

Anyone familiar with classical French cuisine knows that mirepoix, consisting of a mixture of carrots celery and onions, is a common flavor base for stocks, sauces, soups, stews, casseroles and braises. 

When making brown stock, for instance, mirepoix is first scattered in with the beef or veal bones for roasting, and then afterward, the bones are simmered in water with fresh mirepoix. Making a demiglace involves thickening and reducing that stock, along with still more mirepoix, until it's dark, rich and brimming with flavor. It truly forms the backbone of French cuisine. 

The Cajun trinity plays much the same role in Cajun and Creole cooking. 

And in case your wondering, the expression "holy trinity" as it applies to Cajun cooking is thought to have originated with famed New Orleans chef Paul Prudhomme, who specialized in Cajun and Creole cuisines. 

Cajun and Creole Cuisine

Cajun and Creole cuisine are both native to Louisiana, and while they are not exactly the same, they do share many elements, and indeed whole dishes, although they may be prepared slightly differently. 

The Cajun people descended from French Canadian settlers, known as Acadians, while the Creole are a loosely defined ethnic group, including Native Americans as well as immigrants with roots in Africa, the Caribbean, France and Spain. 

In terms of their cuisine, Cajuns and Creole naturally share many elements. For instance, gumbo can be either a Cajun dish or a Creole dish, depending on how it's prepared. The same is true for jambalaya. Cajun cuisine emphasizes smoked meats and sausages, while Creole cooking prominently features ripe tomatoes and rich sauces, as well as seafood. 

You could think of Cajun cooking as rural, with the Acadian settlers adapting traditional French cooking traditions to their new life in the southern Louisiana bayou, with a lot of one-pot meals prepared from wild game and seafood; and Creole, centered in New Orleans, as urban, combining elements of French, Spanish, African and Caribbean cuisines. 

And while both traditions apply techniques from their French antecedents, like in their shared use of roux, for instance (Cajun roux is typically cooked to a darker color than Creole, but they both use it), when it came time to adapt mirepoix, something strange happened: they swapped the carrots for bell peppers. 

Whether this is because carrots wouldn't take to the soil, or simply because bell peppers were plentiful and carrots weren't, isn't clear. It likely had something to do with the fact that Spanish cuisine uses a similar flavor base, called sofrito, consisting of onions, garlic, bell peppers and tomatoes. 

What is clear is that the Louisiana version of mirepoix is as much a backbone of Cajun and Creole cooking as the original carrots, celery and onion version is to French.

Using the Cajun Trinity

Using the Cajun trinity is a way of building flavors in a dish. To make a traditional gumbo with shrimp and sausage, you'd start by prepping your trinity in a 2-1-1 ratio, meaning two parts onion to one part each celery and bell pepper. In this case that would equal one large yellow onion (chopped), one medium bell pepper (cored and chopped), and about two stalks of celery (chopped). 

Once your trinity is chopped, sauté it in olive oil until the onions are translucent, then you'd add some minced garlic along with your seasonings, like salt, pepper, cayenne, and paprika. Reduce the heat, add some butter, then stir in an equal amount of flour to form a roux. Cook for a few minutes, then stir in chicken stock and crushed tomatoes and bring to a simmer. Finally, add your shrimp, simmer until cooked through, then finish with your diced sausage. 

Some cooks add red bell pepper and garlic to their trinity, but of course, this is more than three ingredients and as such is no longer a trinity. 

By the way, there is also a trinity of Cajun spices, namely, cayenne, black pepper and white pepper; as well as a trinity of herbs, consisting of oregano, bay leaf and parsley.