Roux is cooked to a tan color to thicken a recipe. The darker the color of the roux the less thickening power and the more flavoring potential it has.
Cajun cuisine is typically made with oil and is cooked a dark brown—even black by some accomplished chefs—and is used to flavor the dish.
It is used in Cajun dishes to prepare gravies, sauces, soups and stews and of course, the Cajun specialty of gumbo.
There is no set recipe for gumbo. Every restaurant has its own carefully guarded secret recipe and every family follows a traditional family recipe, usually handed down from generation to generation.
Gumbo is made with chicken, chicken and sausage, seafood, pork and even catfish or shrimp gumbo. The one constant is okra and lots of it. Most people in the South also believe file seasoning powder is a must. File has been used for generations and is made from the leaves of the Sassafrass tree.
Beyond that, people argue over using a chicken base or one of oyster liquor. Rice soaks up flavor and is used as the body of the gumbo.
The rest of the ingredients are up to the chef, but it is always a rich, filling and fragrant stew.