7 Ways to Thicken Sauce, Soup, Stew, & Gravy

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The whole point of a sauce, a stoup, a stew, or a gravy is to deliver as much flavor as possible by literally coating the inside of your mouth with the taste of the food. That’s why it is important to know ways to thicken sauce, soup, and gravy.

That’s why I’ve always preferred thicker mixtures that have a little “staying power” once they hit your tongue rather than thin, watery mixtures that simply run down your throat without sticking around at all.

In this post, I’ll go over some hot tips on how to thicken sauce of any sort. 

About Thickening Sauce

Almost all of these methods for how to thicken sauce rely on the principle of adding some thickening agent.

It may be something like flour or starch that already has a thick, gooey consistency when it is added to the sauce. It might also be something like butter or egg that has a liquid consistency when the sauce is cooking but will really start to harden when it is removed from heat.

Although all of the methods I’ll go over will work with any kind of sauce, they each work best with certain kinds of soups, stews, gravies, or condiments. I’ll list those “best-case uses” under the sections for the methods.

7 Methods for How to Thicken Sauce

Flour to Thicken Soup and Sauce

Make a roux by adding equal parts flour and water in a saucepan. You want to prepare two ounces of roux for every cup of sauce you want to thicken, so measure accordingly. Not only do flour and water instantly bond together like magic to create a thick gooey mixture, but it will also impress your friends, family, or whoever eventually eats the dish—if there’s one thing I’ve learned in my decades of cooking experience it’s that French stuff is a crowd-pleaser.

Now add the roux to the sauce, remembering the two ounces per cup of liquid rule. Stir it around so it’s dispersed evenly throughout the sauce, and viola! Your mixture is now thicker.

If you’re in a hurry for some reason, you can simply add water and raw flour to the pan at a quantity of one ounce each for each cup of sauce. The thickener won’t have the same rich flavor as a roux if you do that, though.

Best For: Sauces that already have a rich, cloudy appearance. A good rule of thumb is not to use flour as a thickener in sauces that are already transparent or even translucent. Usually, these dishes will already contain some flour.

Cornstarch to Thicken Sauce

First, make a “slurry” with the cornstarch by mixing equal parts cornstarch and water and beating it until smooth. A fork is the best tool for the beating; if you use a whisk, the slurry will just get caught inside the wire beaters.

After preparing the slurry, whisk it into your sauce over high heat. Since corn starch is flavorless, you can keep adding until you reach the appropriate thickness. It’s a nice perk, because it allows you to “personalize” the way in which your sauce will come out more so than a flour-based roux

Best For: Sauces with a delicate flavor profile that you don’t want to alter at all. While thickening with cornstarch might make your mixture a little lighter in color, it won’t affect the flavor. Also, corn starch thickener does not work with cold sauces.

how to thicken sauce

Tomato Paste

This is a very simple method: simply whisk in tomato paste (not to be confused with tomato sauce or tomato juice) until the mixture is at a desired thickness.

The catch is that you have to add it early so that the tomato in the paste has time to cook along with the rest of the sauce. Adding the paste late into the recipe will not exactly ruin the sauce, but it will give the sauce a tart raw tomato flavor that’s less pleasant than cooked tomatoes.

Best For: Sauces that already have tomatoes in them or that you don’t mind giving a tomato-y flavor. Remember that red is a dominant color, too, so tomato paste will definitely change the color of the sauce if it’s not red already.

Reduce Liquid

This is the only method on this list that doesn’t involve adding anything to the sauce to thicken it. Instead, you are removing liquid from the sauce. This can be accomplished by leaving the sauce over a low flame. While it simmers, liquid will slowly evaporate. Give the sauce a stir every few minutes to see if it is at the thickness you want.

This thickening method will take a bit longer than the others. Resist the temptation to turn the heat higher, though. Even though it will speed up the process, it might overcook the sauce and will likely cause you to miss the window when the sauce is at just the right thickness.

Best For: Any sauce that has a lot of liquid in it, i.e. a soup with a thin broth.


If you’re thickening a sauce that’s still cooking, just add a chunk of butter and stir while it melts in the sauce. If the sauce is already cooled, melt the butter in a saucepan and stir it into the sauce.

The amount you add is up to how thick you want the sauce, but it’ll probably be more than you think – I often add 1.5 tablespoons per cup of liquid. Keep in mind that the butter’s full thickening effect will not kick in until after it cools down and congeals.

This is my favorite method since I love the taste of butter so much.

Best For: Sauces like dips and gravies that won’t be piping hot when served.

salted and unsalted butter in butter dish

Add Egg Yolk to Thicken Sauce

First, separate the yolk from the white of the egg (or eggs, if you’re making more than two cups of sauce). There are a few ways to do that, but my preferred way is cracking the shell and then carefully transferring the yolk from one half of the shell to the other until the white falls away.

After isolating the yolk, whisk it and put it in a bowl. Now for the trick most amatuer chefs might not think of: mix in a bit of the still-hot sauce you’ll be thickening to the yolk. The heat of the sauce will keep the egg yolk from instantly hardening once you add it to the whole pot of sauce.

Now add the egg yolk mixture to the sauce and mix it in.

Best For: Sauces like custards and cream-based salad dressings that already have a rich and eggy flavor profile.

Add Pureed Vegetables

Using a food processor or a powerful blender, process some vegetables into a puree. My favorite vegetables to use in this step are carrots, tomatoes, peas, and celery. Of course, you can choose which vegetables to use based on the flavor profile you’re going for. Whatever you use, though, make sure you’ve already cooked the vegetables so they’re soft enough to puree.

After you have the puree, just mix it into the sauce.

This method not only tastes great in the right kinds of sauces, but it adds to the nutritional value of the sauce.

Best For: Vegetable-based soups and stews, spaghetti sauce.

⭐️ Be sure to check out our other How To posts — and ingredient substitution suggestions! ⭐️

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