The aromatic vegetables bell pepper, onion, and celery are called by some chefs the holy trinity of Cajun cuisine. Finely diced and combined in cooking, the method is similar to the use of the mire poix in traditional French cuisine — which blends finely diced onion, celery, and carrot. Characteristic seasonings include parsley, bay leaf, "onion tops" or scallions, and dried cayenne pepper. The overall feel of the cuisine is more Mediterranean than North American.

Cajun cuisine developed out of necessity. The Acadian refugees, farmers rendered destitute by the British expulsion, had to learn to live off the land and adapted their French rustic cuisine to local (i.e. Louisiana) ingredients such as rice, crawfish, and sugar cane. Many households were large, consisting of eight to twelve people; thus, regardless what other vocations may have been followed by the head of household, most families also farmed. Feeding a large family, all of whose members did hard physical work every day, required a lot of food. Cajun cuisine grew out of supplementing rice with white meat, game or other proteins were available such as crawfish or any other type of river creature.

Cajun methods of preparation

• Barbecueing - similar to "slow and low" Texas barbecue traditions, but with Cajun seasoning.
• Boiling - as in boiling of crabs, crawfish, or shrimp, in seasoned liquid.
• Deep frying
• Étouffée - cooking a vegetable or meat in its own juices, similar to braising or what in New Orleans is called "smothering".
• Frying, also known as pan-frying.
• Grilling - faster than barbecueing.
• Injecting - using a large syringe-type setup to place seasoning deep inside large cuts of meat.
• Smoking - for flavoring, cooking or preserving meats.
• Stewing, also known as fricassee.

Deep-frying of turkeys or oven-roasted turduckens entered southern Louisiana cuisine more recently. Also, blackening of fish or chicken and barbecuing of shrimp in the shell are excluded because they were not prepared in traditional Cajun cuisine. See Misconceptions below.

Cajun ingredients

The following is a partial list of ingredients used in Cajun cuisine and some of the staple ingredients of the Acadian food culture.

Grains

• Corn
• Rice — long, medium, or short grain white; also popcorn rice

Rice proved to be a valuable commodity in early Acadiana. With an abundance of water and a hot, humid climate, rice could be grown practically anywhere in the region, and grew feral in some areas. Rice became the predominant starch in the diet, easy to grow, store, and prepare. The oldest rice mill in operation in the United States, the Conrad Rice Mill, is located in New Iberia.