How to Thicken Sauce

Ever end up with a thin, watery sauce instead of a creamy, velvety one? Thankfully, there is a myriad of ways to address the problem. Whether it's a mac and cheese, marinara, or BBQ sauce, we've got the fix you need. 

What Equipment Do I Need?

Thickening a sauce does not require any expensive equipment. All you need is a bowl, a whisk, and a saucepot. For most of the following techniques, a whisk is critical in removing any lumps from the liquid and ensuring a smooth, velvety sauce. 

How to Thicken Sauce Through Reduction

The easiest way to thicken a sauce is to reduce the liquid in a pot on the stovetop, widely used in slow-simmered ragus or pan sauces. 

For a ragu, you typically add wine or stock to browned meat, then let the sauce simmer to develop the flavors. At first, the liquid appears thin and watery, and as the water evaporates, it thickens nicely to coat each bit of meat.

You can apply the same principle to any sauce reduction:

• Simmer the sauce in a sauce pot until it reaches your desired consistency. 
• Make sure to keep the pot uncovered to allow excess liquids to evaporate. 
• Avoid boiling the liquid to prevent any curdling or sauce separation.
• Keep in mind that simmering intensifies the sauce's flavors. Depending on how long you reduce the sauce, you may want to hold back on the salt (or use low-sodium broth) so that the mixture doesn't taste too salty. 
• Optionally, purchase a splatter guard to prevent sauces from splattering everywhere.

This method is great for:

• Tomato-based sauces such as marinara sauces, meat sauces, or curries
• Pan sauces and braising liquids
• Glazes (balsamic or honey soy) and BBQ sauces
• Reducing heavy cream to create a thicker sauce base for pizza or pasta 

How to Thicken Sauce with Cornstarch

Cornstarch (and other starches, such as arrowroot or tapioca) are powerful thickeners. Adding just a small amount into a sauce can quickly and easily change the consistency of the dish. Do note that acid (lemon juice, tomato sauces, etc.) weaken cornstarch's thickening abilities, so an alternative should be considered in those cases. 

To use cornstarch as a thickener, try the following steps:

1. Make a cornstarch slurry: In a small bowl, whisk the cornstarch with an equal amount of cold liquid until dissolved. This step helps prevent any clumping. 
   
2. Add the cornstarch slurry into the sauce and bring the mixture to a boil, constantly whisking until fully incorporated. Boil for 1 to 2 minutes until the mixture has thickened. Note that cornstarch needs to boil to thicken correctly. 
   
3. Do not continue to boil after thickening. Boiling after the additional few minutes needed to thicken the sauce will cause the cornstarch to thin out again. 

If you're not sure how much thickener to use, you can always add a little bit of the slurry at a time to the liquid and adjust as needed. ArgoStarch recommends 1 tablespoon of cornstarch per 1 cup of liquid for a thinner sauce and 2 tablespoons cornstarch per 1 cup liquid for a gravy-like consistency. 

This method is great for:

• Stir-fry dishes, especially in Chinese cooking
• Gravies
• Curries

How to Thicken Sauce with Flour

If you don't have cornstarch on hand, you can use the same slurry techniques outlined above. However, flour has a weaker thickening power, so for every 1 tablespoon of cornstarch, substitute 2 tablespoons of flour. 

You may be wondering why some recipes call for a flour-based slurry while others recommend a flour-based roux (a paste made from cooked butter or oil and flour). 

Two key differences can help guide you to pick one method or the other:

1. A roux is traditionally considered the base (or starting point) for dishes such as a béchamel or gumbo. The cooked flour and fat base add a complex flavor to the rest of the dish. In theory, you could add the roux at the end of the cooking process, but you would miss some of that flavor development. On the other hand, a slurry is most often added at the end of the cooking process. 
   
2. A roux adds an intricate, nutty flavor to the sauce. Depending on the dish at hand, you may want that flavor -- or you may want the neutral taste of a slurry.
   

This method is great for:

• Béchamel, mornay, and other cream-based sauces.

Additional Ways to Thicken Sauces

• Eggs: Carbonara, aiolis, and hollandaise all have one thing in common: their thick, glossy textures could not come together without the use of eggs as a thickener. With raw sauces, like an aioli, whisking eggs vigorously with the addition of oil creates a creamy, voluminous emulsion. In cooked sauces, you temper the eggs to prevent them from curdling.
  
  To temper the eggs, whisk small amounts of hot liquid into the egg mixture until the egg mixture reaches the same temperature as the sauce. Then, slowly whisk the egg mixture into the sauce at a lower heat to prevent curdling. 
  
  
• Beurre Manie: A beurre manie is a hand-kneaded paste of butter and flour. Slowly whisk the paste into a sauce and let boil for 1 minute until thickened.