Quick Microwave Roux
The "emergency roux" method is easier than using the stovetop for cooking small amounts.
Roux, a cooked mixture of flour and fat, is often used to thicken sauces and stews. It makes an appealing thickener because cooking takes the raw edge off the flour and gives it a nutty, toasted flavor. But a roux is prepared at the start of a recipe, before liquids and other ingredients are added to the pot. What happens if you get to the end and find that your stew or sauce is too thin? You could whisk in a cornstarch slurry, but this tends to produce a tacky, shiny result (think stir-fry sauces). An uncooked roux, or beurre manié, is also less than ideal, since it brings a raw flour taste to the dish.
A better option: Make a quick roux in the microwave, which is easier than using the stovetop for cooking small amounts. We tested “emergency roux” made with oil and butter and settled on the oil version since it required less stirring. To make 1/4 cup, follow the steps below. Make sure to use a microwave-safe measuring cup or bowl. We recommend placing it on a dry dish towel when you remove it from the microwave since it’s best to avoid placing very hot tempered glass directly onto a cold surface.