How to Make a Cornstarch Slurry

Unlock the full potential of your kitchen with our guide on how to make a cornstarch slurry. From thickening sauces and gravies to achieving perfect consistency in your baking recipes, this versatile and easy-to-make ingredient will become your secret weapon in the kitchen.

Have you ever been cooking a soup or other recipe that is turning out with just a bit too much liquid than you’d prefer? You could let it simmer down until the mixture is the consistency you’re looking for or you could learn how to make a cornstarch slurry.

In my kitchen, cornstarch – called corn flour outside of the US – is a gluten-free, fine white powder staple ingredient and yes, it gets used a lot. A cornstarch slurry is a quick and easy way to fix how thick a soup, sauce or other recipe is.

What is a Cornstarch Slurry?

Honestly, a cornstarch slurry is simply water and cornstarch mixed together. When added to a simmering liquid, science happens and it acts as a thickening agent and will thicken any hot liquids you add it to. At that point, simply finish cooking your meal to the desired consistency and eat!

It’s a fantastic way and a pretty common thickening agent used in kitchens world wide. The thickening properties are great for helping to create a flavorful sauce that doesn’t lose flavor – or take on a starchy taste – because it has too much water content in it.

Also, don’t ask about the science behind it. I’m a writer; not a scientist. I just know it works. 😁

What Can a Cornstarch Slurry Be Used to Thicken?

A slurry has a whole wide array of things it can be used for. This can include thickening soups and stews, making gravies, and more. Some pie fillings, like my peanut butter meringue pie recipe does.

It’s also great for creating a thick sauce in recipes such as beef stew or in sweet sauces like a lot of American Chinese food uses.

Finally, it’s super simple to make a meat based cornstarch gravy with a slurry. Just use some of the pan drippings and cornstarch to create a roux. Once you’ve done that, add a few parts liquid and heat until your gravy is as thick as you’d like it to be.

Tips for Making a Cornstarch Slurry

When you make your cornstarch slurry, you’ll want to use a wire whisk and to make sure you mis the ingredients well enough that you don’t have any clumps of powder. Leaving lumps behind will cause the slurry to not thicken as well as you want it to.

You should also use very cold water. All that science stuff I mentioned requires it to get the thickening reaction that you want. It will thicken with water that isn’t as cold, but it will take longer. I usually throw my water into a small bowl in the freezer for a few minutes before I make mine.

Add the slurry to your pot or pan slowly. I say this because if you add too much, what you’re cooking could turn out far more thick than you intended it to be.

Lastly, you may want to play with the ratios that you’re using. I personally use equal parts cornstarch and water, but others prefer different ratios. Some prefer to use one tablespoon of cornstarch to two tablespoons water. This won’t hurt your slurry, but you should know that the more water your slurry has, the longer it will take to work.

Alternatives to Cornstarch in a Slurry

If you don’t have or don’t want to use cornstarch in your slurry, there are a few cornstarch alternatives you could use.

The first is the simplest, but also the one that is not gluten free. Simple all-purpose flour made with the same ratio as a cornstarch slurry will do the same thing for your dish by creating a roux. Since flour is not gluten free and has more carbohydrates than cornstarch, I typically stay away from using it.

Arrowroot powder, Tapioca Starch and Xanthan gum are also cornstarch alternatives. Xanthan gum specifically is both gluten free and low carb, but you will need to really play with the amount since it can be much harder to use without your final dish having a spongy texture or becoming gummy.

Making a cornstarch slurry is by far the easiest out of the four options you have. Since it takes less than two minutes to make, you can whip it together quickly without any trouble at all.