How to Thicken a Sauce, Soup, or Stew

Thickening is not one technique. Reduction concentrates flavor. Starch adds body without removing water. Puree makes a dish feel substantial. Dairy, egg, or butter can add richness as well as texture. Choose the method by what the dish can tolerate.

Reduce when the flavor can become stronger

Simmer uncovered so water evaporates. Use a wide pan for speed and stir more often as the liquid concentrates. Reduction works well for pan sauces, tomato sauces, broth, and braising liquid.

Taste before reducing heavily. Salt, sugar, bitterness, and spice all become more concentrated. If the dish is already salty, use a thickener instead.

Use starch for predictable body

For a flour roux, cook roughly equal parts flour and fat before whisking in liquid gradually. The longer flour browns, the more flavor it gains and the less strongly it thickens.

For cornstarch, mix it first with cool water into a smooth slurry. Whisk a small amount into simmering liquid and allow it to activate before deciding whether to add more. Do not sprinkle dry starch directly into a hot pot.

Potato starch and arrowroot behave differently from flour and cornstarch; follow package guidance and avoid prolonged boiling when it weakens their texture.

Use the food itself

Blend part of a bean soup, mash a few potatoes, puree cooked vegetables, or simmer rice, lentils, or bread into the liquid. This produces body that belongs naturally to the dish. It can dull fresh flavors, so restore acid and aroma at the end.

Finish gently

Cream, yogurt, cheese, egg yolk, and butter can enrich and thicken, but excessive heat may split or scramble them. Temper eggs or yogurt with warm liquid, lower the heat, and avoid a hard boil after adding them.

If a sauce becomes too thick, whisk in water, unsalted broth, milk, or another compatible liquid a little at a time. If it is lumpy, strain it or blend when appropriate. Then taste again—texture changes how strongly salt and acid register.