Roux
Roux () is flour and fat cooked together and used to thicken sauces. Roux is typically made from equal parts of flour and fat by weight. The flour is added to the melted fat or oil on the stove top, blended until smooth, and cooked to the desired level of brownness. Butter, vegetable oils, bacon drippings or lard are commonly used fats. Roux is used as a thickening agent for gravy, sauces, soups and stews. It provides the base for a dish, and other ingredients are added after the roux is complete.
Étouffée
Depending on who is making it and where it is being made it is flavored with either Creole or Cajun seasonings. Although Creole and Cajun cuisines are distinct, there are many similarities. In the case of the Creole version of crawfish étouffée, it is made with a blonde or brown roux and sometimes tomatoes are added. A blond roux is one that is cooked, stirring constantly, for approximately 5 minutes to remove the "raw" flavor of the flour and to add a slightly "nutty" flavor, while a brown roux is cooked longer (30 to 35 minutes) in order to deepen the color and flavor.