How to Thicken a Sauce, Soup, or Stew

Thickening is not just one technique. Reduction concentrates flavor by removing water. Starches, such as cornstarch, add body without removing water. Puree makes a dish feel substantial with the same ingredients. 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 to let water evaporate. Use a wide pan for speed and stir more often as the liquid concentrates. This keeps all spices and any solids mixed thoroughly, preventing sticking to the sides and burning on the bottom of the pan. 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 and prominent as the liquid reduces. If the dish is already salty, use another thickening method instead.

Use starch for predictable body

For a flour roux, cook roughly equal parts flour and fat before whisking in liquid gradually. A roux is generally created at the beginning of a meal to let the flour brown. The longer flour browns, the more flavor it gains but the less strongly it thickens.

For cornstarch, mix it first with cool water into a smooth slurry. Whisk a small amount into simmering liquid, bring to a boil, and allow it to activate before deciding whether to add more. Sprinkling dry starch directly into a hot pot will lead to clumps and can cause the starch not to thicken correctly.

Potato starch and arrowroot, normally added in a slurry form, are less common in everyday cooking and are more difficult to find, but they can act as a substitute for a flour roux. Follow package guidance and avoid prolonged boiling as it weakens their thickening power.

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. This method 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.