A good roux—a slow-cooked mixture of flour and fat that's used to thicken and flavor a soup, stew, or sauce—is the foundation of many Cajun and Creole dishes, including the recipe for crawfish etouffee. Depending on how long you cook it, a roux can be light brown and faintly nutty in taste to dark chocolate brown with an intense, almost chicory-like flavor. We asked the New Orleans chef John Besh, author of My New Orleans (Andrews McMeel, 2009), about the finer points of making a roux.
What role does roux play in your cooking? Roux is the basis of all the good stuff I grew up with. It's a ritual. Every cook has a certain pot and a certain wooden spoon to make their roux. Fat and flour are very meager ingredients, but if you take the time to nurture them and understand what you're doing, then you're creating something truly incredible.
How does the choice of fat affect a roux? Chicken, duck, and pork fat all give good flavor. I scrape the layer of fat from the top of chilled chicken stock and use that to make my roux, or you can use canola oil. It works great because of its high smoke point and its neutral flavor.
Can you describe your technique for a dark brown roux? Heat your oil or fat in the skillet or pot over high heat until it almost reaches the smoking point. Then add the flour and listen to it. When you hear the flour sizzling, you know it's cooking. Whisk it. Then lower the flame to medium or medium-low and continue whisking. As long as you're whisking, your roux isn't burning. Keep whisking until you've got a roux that's milk chocolate in color. Then add your onions. That's when you start stirring with a wooden spoon until the onions caramelize and the roux turns a dark chocolate color. Then you stir in your other ingredients.