A cornstarch slurry is a simple mixture of cold liquid and cornstarch used to thicken sauces, soups, gravies, and stir-fry glazes. It works because the cornstarch granules disperse evenly in the cold liquid before hitting heat, preventing lumps and giving a glossy, smooth texture. This technique is a staple in Chinese cooking and is widely used in Western gravies and fruit pies.
Ingredients
- 1 tablespoon (8 g) cornstarch
- 2 tablespoons (30 ml) cold water, broth, or other cold liquid
This makes enough slurry to thicken about 1 cup (240 ml) of hot liquid. For a thicker result, use 2 tablespoons (16 g) cornstarch with 1/4 cup (60 ml) liquid.
Instructions
- Place the cornstarch in a small bowl. Add the cold liquid (water, broth, wine, or juice) and whisk with a fork until the cornstarch is completely dissolved and the mixture is smooth, about 15 seconds. There should be no dry powder at the bottom.
- Pour the slurry into the hot liquid you want to thicken (soup, sauce, gravy, or stir-fry) while stirring constantly. The liquid should be simmering or at least very hot—not just warm.
- Continue to stir and cook for 1–2 minutes. The liquid will thicken as it returns to a simmer. Do not boil vigorously for more than a minute, as this can break down the starch and thin the sauce.
- Remove from heat and use immediately. The sauce will thicken further as it cools slightly.
Tips
- Always use cold liquid. Hot liquid will cause the cornstarch to clump instantly. Use cold water, broth, or even milk straight from the fridge.
- Whisk just before adding. Cornstarch settles quickly, so give the slurry a quick stir right before pouring it into the pot.
- Don’t overdo it. Start with 1 tablespoon of cornstarch per cup of liquid. You can always add more, but you can’t remove it. If the sauce is too thick, whisk in a little hot water or broth.
- Substitution: For a gluten-free alternative, use arrowroot powder in the same ratio. For a grain-based thickener, use all-purpose flour, but mix it with an equal amount of cold water and cook longer to avoid a raw flour taste.
Serving Suggestions
Use the slurry to thicken beef stew, chicken gravy, sweet-and-sour sauce, fruit pie fillings, or Asian stir-fry sauces like teriyaki or kung pao. It also works well for thickening fruit compotes and dessert sauces.
Variations
- Flavored slurry: Replace water with cold broth, wine, or citrus juice to add flavor without diluting the sauce.
- Extra glossy: For a shiny, restaurant-style finish, use a slurry made with cold stock and add a small knob of butter at the end.
- For pies: Use a slurry of cornstarch and cold fruit juice to thicken fruit fillings before baking.
Storage and Reheating
Cornstarch slurry is best used immediately; do not store it, as the cornstarch will settle and may not re-dissolve evenly. If you have leftover thickened sauce, store it in an airtight container in the refrigerator for up to 3 days. Reheat gently on the stovetop over low heat, stirring constantly. If the sauce thins out after reheating, you can whisk in a fresh slurry (1 teaspoon cornstarch mixed with 2 teaspoons cold water) and simmer for 1 minute. Do not freeze sauces thickened with cornstarch, as freezing can break the starch gel and cause separation.
Frequently Asked Questions
Why does my slurry turn lumpy? Lumps happen when you add the slurry to hot liquid too quickly or don’t stir enough. Always whisk the slurry into the hot liquid slowly while stirring constantly, and make sure the slurry is fully dissolved before adding.
Can I use hot water to make the slurry? No, hot water causes the cornstarch to gelatinize instantly, forming clumps. Always use cold liquid.
How much slurry do I need for 2 cups of sauce? Use 2 tablespoons (16 g) cornstarch mixed with 4 tablespoons (60 ml) cold liquid for a medium-thick sauce. For a thicker gravy, use 3 tablespoons (24 g) cornstarch.
Can I substitute flour for cornstarch? Yes, but flour needs double the amount (2 tablespoons flour per 1 tablespoon cornstarch) and must be cooked for at least 5 minutes to remove the raw taste. The sauce will be less glossy and more opaque.
Why did my sauce turn thin after cooking? Overcooking or boiling vigorously can break down the starch, causing the sauce to thin. Simmer gently and remove from heat as soon as it thickens.
Can I use cornstarch slurry to thicken cold liquids? No, cornstarch needs heat to activate its thickening power. For cold puddings or sauces, use gelatin or agar-agar instead.
Related
- Kentucky Benedictine Tea Sandwiches Recipe
- Kentucky Derby Tea Sandwiches: Classic Recipes
- How Long to Bake Chicken Tenders: Juicy Every Time
More recipes to cook
Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes
Spotted an error? Tell us and we will correct it (corrections policy).