Technique #12: Make Roux for Rich Sauces

The gentle thickening power of flour is the ideal choice for such sauces in long-simmered or baked dishes, where a thickener such as cornstarch would turn the sauce gummy and gelatinous.

Making a roux basically involves cooking flour and fat together before adding the liquid that you want to thicken. The goal of the first step is twofold: to cook the raw, starchy flavor out of the flour and to coat the flour granules with the fat in order to create a smooth paste and to keep the particles separate so they will disperse evenly in the liquid and not aggregate into dry lumps.

In French cooking, roux is often cooked only briefly, to a white, blond, or light brown shade. Butter is often the fat of choice. In Southern cooking (particularly Cajun and Creole), roux is cooked for a much longer time, to a much darker brown, in order to add a toasty, nutty flavor to dishes. In this case, oil (or bacon fat!) is typically employed.

The darker the roux, the more pronounced its flavor, but the darker it gets, the more compromised its thickening power becomes—so it’s important to cook roux to the specified color.

Cook the white roux for a béchamel in mac and cheese or soufflé for too long and it won’t have the proper thickening power or structural integrity—your pasta will be soupy or your soufflé won’t rise. And if you shortchange the cooking time for the dark roux in a Louisiana gumbo recipe, you’ll end up with a gluey, gloppy dish without that deep flavor that characterizes gumbo.

A Southern-style dark brown roux traditionally takes an hour of hands-on cooking time. Using a renegade technique, we developed a streamlined, hands-off “dry roux.” We toasted flour, without fat, in the oven until it turned dark brown. Since there’s no fat, this would be difficult to incorporate into a recipe without clumping, so we first whisk it with a bit of liquid before adding it to the pot.