There’s nothing like a bowl of soup to warm you up from the inside out. And a silky, spoon-coating texture — rather than a thin, watery consistency — matters just as much as flavor.
“The perfect thickness where a soup coats the mouth can really make or break the overall experience,” says Ian Rough, executive corporate chef at Cameron Mitchell Restaurants.
Beyond traditional dairy-based thickeners like cream, there are a number of ways to add body and viscosity to soups, from cornstarch and roux to starchy vegetables and more. To help you narrow down your options, we asked chefs for their go-to thickening agents and when to use each one. Read on for the best thickeners, whether you’re making gumbo, seafood bisque, or hot and sour soup.
5 ways to thicken soup
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Roux
Roux is a classic cooked mixture of flour and fat. “Roux is perfect for hearty soups like New England clam chowder or gumbo,” says John Ho, chef and manager at FLIK Hospitality Group and chef with Resident. “You can really vary the flavor by cooking the roux less or more,” he adds, which “also changes the thickening ability of the roux and the flavor it brings to the soup.” In the case of a robust gumbo, a beautiful deep brown roux is optimal as a roux cooked longer gains thickening power.
When working with roux, it’s essential not to rush the process. “Adding small amounts of the liquid to the roux and whisking or stirring very well until fully combined helps greatly to ensure a smooth incorporation,” advises Rough. Be sure to allow for adequate simmer time for the most developed flavor.
“Once a roux is added, it needs time to cook out so the soup does not taste floury,” says Glenn Rolnick, chef and executive director of culinary operations at Alicart Restaurant Group, which includes Carmine’s.
Pro tip
Don’t start with too much thickener: “When it comes to texture and using thickeners, it’s all about how much you use,” Rough points out. “Too much roux and a soup gets pasty, too much cornstarch or arrowroot [a powder often used in gumbo] and a soup gets slimy, too much reduction of cream or potato puree and a soup can be gloppy.”
Cornstarch
In contrast to roux, “cornstarch is great when you want to thicken a clear broth without adding flavor,” notes Ho. Think egg drop soup. “It keeps the soup bright and clean while giving it the right texture.”
To prevent clumping, make a quick slurry first. “I like to use just enough water to get the cornstarch smooth, as you don’t want to add unneeded water to your soup,” Rough says.
Since cornstarch only needs to be briefly boiled to unlock its thickening abilities, add the slurry towards the end of cooking, about one tablespoon at a time. “I get the soup fully cooked to the flavor profile I am trying to get to, finish with the slurry, and then just bring [the] soup to a boil,” explains Rough.
If your soup is still too thin, “Gently reboil and add a little more of the cornstarch-water blend, bringing it back to a five-second boil,” says Rolnick.
Starchy vegetables
“Using the thickening power of the natural starches in some ingredients can be great as well,” says Rough, who points to potatoes and corn as “vegetables that can help thicken soups without having to use other starches.”
Vegetables with lower starch content can also help you achieve a rich, luxurious mouthfeel if you cook and blend them in for recipes like Silky Cauliflower Soup.
Even when starchy vegetables are left in chunks rather than pureed into the soup, it’s important to keep their downstream thickening effects in mind. Rolnick leans on roux to thicken his chowders, but “also [takes] into consideration the potatoes cooking in the soup, which add to the texture and thickness.”
Pro tip
Troubleshoot the consistency as needed: “If the soup is too thick, loosen it with more stock or whatever liquid you used originally,” Ho advises. If you’re dealing with the opposite problem, Rough recommends “either [reducing] the soup down to thicken slightly or [adding a] small amount more of the same thickener to get it to the right consistency.”
Rice and beans
“I’m a fan of using starches such as beans or grains to naturally thicken your broth,” says Joe Anthony, managing partner and executive chef at Arvine in New York City. “You can allow them to break down in your stock as they release their starch, or blend a little into your stock if you want it to be thicker.”
Rice in particular is ideal for adding velvety body to seafood bisques. “Cooking [rice] until tender and pureeing [until] smooth is a great way to thicken a soup and stay gluten-free when needed,” says Rough.
Xanthan gum
In addition to roux and cornstarch, Ho regularly leans on xanthan gum, “a hydrocolloid produced by fermenting sugars with a specific strain of bacteria,” as an extremely effective (and allergy-friendly) thickener.
“One of its biggest advantages is that it thickens in both hot and cold preparations,” Ho explains. “For example, a chilled soup like a thin vichyssoise doesn’t need reheating to activate a starch — you can simply blend in a small amount of xanthan gum to reach the perfect consistency.”
The versatile ingredient also helps bartenders blend up extra-creamy frozen cocktails. You can find it on Amazon or from brands like King Arthur.
Pro tip
Strain pureed soups: “For an extra-smooth texture, you can strain the soup through a mesh strainer afterward to catch any unblended bits or small clumps,” Ho suggests.
What’s the best blender to use for soup?
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Immersion blender
Though a countertop blender delivers power and speed at the touch of a button, Rolnick prefers an immersion blender (sometimes called a hand or stick blender) for its ease of use, especially when emulsifying large amounts of hot ingredients.
“When you don’t have to transfer hot liquid from a pot to a blender, it’s safer from hot spillage and saves a step,” he explains. “Many times, cooks don’t realize how quickly the liquid rises in a stand blender when you turn it on, especially if it’s overfilled, [which causes] a hot mess on your countertop.”
High-speed blender
If you don’t mind waiting for your soup to cool slightly and blending in batches, a high-speed blender may produce an overall smoother consistency than its handheld counterpart without the babysitting.
No blender
Depending on the type of soup you’re making, you might not need a blender at all. “If you are thickening a chunky soup, you can’t use a blender or immersion blender in the soup as it will puree the garnish,” says Rough, who tempers and whisks the thickener into the pot in these cases.
“When using a roux to thicken, and there aren’t dense vegetables or starches in your product that you want to incorporate, a blender isn’t necessary,” Rolnick adds. For cornstarch-thickened soups, too, simply stir in the (well-combined) slurry and let it work its magic.
