How To Thicken Sauce With Cornstarch

Cornstarch is a common thickening agent, but if you add it directly to the liquid you want to thicken, it will clump up. To thicken a sauce or soup with cornstarch, you first need to make a slurry, which is a mixture of equal parts cornstarch and liquid (usually water, stock or wine). It's important to make the slurry with cold liquid, and then add the slurry to the simmering sauce.

What Is Cornstarch?

How Cornstarch Works

The cornstarch molecules are like little sponges. They soak up water and expand as they do so. The same thing happens with any starch. It's the same way rice, oatmeal, or polenta thickens and expands in volume when simmered.

How to Make a Cornstarch Slurry

Cornstarch imparts a glossy sheen to the liquids it thickens, so it tends to be used more in sweet sauces and pie fillings than in savory sauces and gravies. Still, it works really well, and it's easy to use. A general rule of thumb, is 1 tablespoon of cornstarch whisked with 1 tablespoon of cold liquid for every cup of liquid you are trying to thicken. Whisk the slurry into the hot, simmering liquid that you want to thicken.

We created a simple cornstarch slurry recipe to use for 2 cups liquid, but feel free to adjust ratios as needed.

How to Use Cornstarch Thickener

Uses range from everything from sauces, soups, gravies, and more. Cornstarch can be used to make a quick gravy sauce if your meat dish needs a little extra flavor. In that case, use chicken stock for your slurry instead of water. Once the slurry is made, add in any meat drippings or small bits from the pan.

Suppose you're making a stir-fry, and it's become watery—this often happens when your wok or pan isn't hot enough. You could let it reduce, but you'll just overcook your veggies. Instead, add a cornstarch slurry and all that extra liquid will thicken into a flavorful sauce.