Three Ways to Thicken Sauce (Cornstarch, Roux, Beurre Manie)
When your sauce, gravy, or stew doesn't turn out quite as thick as you'd hoped, you have a few options: A cornstarch slurry will create a thicker consistency, but imparts a glossy sheen that is not always wanted. A roux can also be used, but making roux takes time and a second pan. Instead, consider a beurre manié. This mixture, whose name means “kneaded butter” in French, is a paste of flour and butter that's added to hot liquid. If flour were added directly to hot liquid, it would clump; in a beurre manié, the flour particles are coated in fat, so as the butter melts, it seamlessly disperses the flour particles, which swell and thicken the liquid.
➢ To make it: Combine equal parts by volume all-purpose flour and softened unsalted butter in bowl. Using spatula or fork, mash to uniform paste. (Paste can be portioned into 1-tablespoon dollops and refrigerated for up to 2 weeks or frozen for up to 4 months.)
➢ To use it: Bring liquid to boil, then whisk in 1 tablespoon beurre manié until completely dissolved. Simmer sauce has started to thicken, 2 to 3 minutes, before adding more.