How to Make a Roux

Makes 1/2 cup

4 tablespoons (1/2 stick) unsalted butter

1/2 cup all-purpose flour

1. Melt 4 tablespoons unsalted butter in a large regular or cast-iron skillet over medium-low heat.

2. As soon as the butter is melted, add 1/2 cup all-purpose flour and immediately stir with a wooden spoon in a figure-eight motion until the flour has completely absorbed all of the butter, 30 seconds to 1 minute. There should be no dry pockets of flour left in the mixture.

3. Continue cooking, stirring constantly, until the mixture is smooth, slightly thickened, and small bubbles begin forming, 30 seconds to 1 minute. The roux should smell nutty and there should be no unincorporated flour left. If any lumps of flour remain, break them up with the spoon.

4. At this point, you have a white roux that is perfect for using in light sauces such as béchamel. For a blonde roux (which can be used interchangeably with a white roux but has a slightly nutty flavor), continue cooking over medium-low heat, stirring constantly, until the roux is a pale golden color, 3 to 4 minutes. For a brown roux (most commonly used to thicken gumbo), cook until the roux is dark brown and very fragrant, 10 to 12 minutes.

Recipe notes: Roux can be refrigerated in an airtight container up to 30 days, and will harden into a firm mass. To use, break off the desired amount and whisk directly into soups, sauces and gravies until completely dissolved.

Cooking oil can be substituted for the butter. Olive oil, canola oil and vegetable oil would all work well in this recipe.

(Jesse Szewczyk is studio food editor for TheKitchn.com, a nationally known blog for people who love food and home cooking. Submit any comments or questions to editorial@thekitchn.com.)