Learn How to Make a Roux for gumbo so you get the best rich Cajun flavor. Simply whisk together flour and either melted butter or oil, then simmer until you achieve a white, blonde, light brown, or dark color for all of your thickening needs.
Heat a pan over medium-low heat. Add butter to it and allow it to melt completely. Sprinkle in flour and begin stirring immediately. Stir constantly to keep from burning. This is great to use as a thickener in soups or sauces.