How to Use Flour or Cornstarch to Thicken Sauce, Gravy, and Soup (2024)

• How to Cook

Have you ever tried to twirl a bite of pasta that, by the time it reaches your mouth, seems to have no sauce? Here are some tips on using flour or cornstarch to thicken sauces—items likely already in your pantry. Improve the viscosity of sauces and gravy, so you enjoy their rich flavor in every bite, and make your soups more substantial and filling with this technique.

How to Use Flour to Thicken Sauce

To use flour as a thickening agent:

1. Use two tablespoons flour mixed with ¼ cup cold water for each cup of medium-thick sauce.
2. Thoroughly mix in the water to prevent lumps.
3. After stirring the combined flour and water into the sauce, cook and stir over medium heat until thickened and bubbly.
4. Heat one minute more to cook the flour thoroughly.

How to Use Cornstarch to Thicken Sauce

Using cornstarch to thicken sauce is very similar to using flour, but you need different quantities:

1. Use one tablespoon cornstarch mixed with one tablespoon cold water (aka a cornstarch slurry) for each cup of medium-thick sauce.
2. Thoroughly mix the cornstarch and water together. Our Test Kitchen recommends shaking the cornstarch and water in a Mason jar for easy mixing. Once combined, pour the mixture into your sauce.
3. Cook and stir over medium heat until thickened and bubbly.
4. Heat two minutes more in order to completely cook the cornstarch.

Substituting Cornstarch for Flour as a Gluten-Free Alternative

If you have someone in the family with an allergy restriction, you may need a gluten-free thickener for your soup recipe. It's important to note that cornstarch has twice the thickening power of flour. If you need to substitute cornstarch to thicken liquid in a recipe that calls for ¼ cup (four tablespoons) flour, you only need two tablespoons cornstarch. If you're substituting flour for cornstarch to thicken the sauce in your recipe, substitute two tablespoons all-purpose flour for every one tablespoon cornstarch.

Other Ways to Thicken Gravy, Soup, or Sauce

There are options other than flour and cornstarch to thicken foods.

• Roux: When it comes to thickening soup and other sauce-based recipes, you can make a roux (a mixture of flour and fat). This is common for creamy soups like baked potato soup and sauces like macaroni and cheese. (Get the full instructions on how to make roux.)
• Eggs: You may have used egg yolks to thicken salad dressings, like a classic Caesar. You can also use egg yolks to thicken sauce. To avoid scrambled eggs, you'll want to temper the yolks first. To temper egg yolks, add about a cup of the hot liquid to the yolk slowly while stirring constantly. Once added, pour the mixture back into the sauce to thicken.
• Pureed Food: This method works particularly well for thickening soups. Simply puree half of the soup and add it back to the rest of the pot. You can also puree beans or veggies and add them to thicken.

Put those thickening skills to good use by making chicken marsala for dinner or a delicious turkey gravy for your Thanksgiving feast.