Whether you want to thicken a sauce, make gravy or bring some soul to a gumbo, you’re going to have to make roux. Roux is a classic 2-ingredient recipe, combining equal parts flour and fat and cooking the two together to unlock their thickening potential. Use white roux to make béchamel (besciamella in Italian!) or cheese sauce, blond roux for your Thanksgiving gravy, and brown roux to add a deep nutty flavor to Cajun and Creole dishes. Roux sounds fancy, but it’s not hard. Here’s the simple and easy technique from Matt Abdoo, chef de cuisine at Del Posto.