What Is a Roux and Why Do I Keep Messing Mine Up?

Butter, flour, and a whole lotta whisking.
What Is a Roux and Why Do I Keep Messing Mine Up
Photograph by Isa Zapata.  Food styling by Micah Morton

Some kitchen skills—like dicing onions, flipping pancakes, or rolling burritos—may feel tricky at first but become muscle memory pretty quickly. But in my experience, learning how to make a roux is not one of those skills. The process itself seems straightforward: Add equal parts fat and flour to a pan on medium low, then stir until uniform and the desired color has been achieved. In practice, however, my rouxs are pretty hit and miss.

Sure, sometimes I’ll nail one on the first try and be on my way to perfect gravy, béchamel, or gumbo. But then there are the times when things keep clumping together, or the mixture comes out super thin, or—worst of all—the flour just burns before it can incorporate into the fat. When that happens, I usually dump my failed attempt (along with my ego) into the trash and start over. But after messing up senior food editor Christina Chaey’s Japanese Curry recipe twice in a row, I realized I needed help from the pro. Here’s everything I learned:

What is a roux?

In the simplest terms possible, a roux is a mixture of equal parts flour and fat, cooked together over low- to medium-heat, to create a uniform thickening agent that’s deployed in saucy recipes like this extra-creamy Lasagna Bolognese, Chicken-Andouille Gumbo, and béchamel-soaked Croque Monsieur.

You have options when it comes to the fat, but more often than not, roux is made from either neutral oil (like vegetable or canola) or unsalted butter. When used in soups, sauces, and casseroles a roux provides creaminess and density, helps incorporate other fatty ingredients like cream or cheese, and generally binds things together into a cohesive finished product. And gravy, this season’s MVP, is made by adding stock and/or meat drippings to a roux.

As the silent “X” in their name implies, rouxs are common in French cuisine—used in mother sauces like béchamel and velouté—but they pop up in dishes from around the world, too. Rouxs are an essential part of Cajun cooking and are also the backbone of many Japanese curries—like Chaey’s winter squash and mushroom curry and the Golden Curry that inspired her recipe.

“If you look at the ingredients on the box [of Golden Curry], it's pretty much just flour and oil, and then you have salt, sugar, and curry powder,” says Chaey. If you want to see the power of a well-made roux, add one of those gorgeous yellow blocks to a pot of veggie broth. It’ll disperse in seconds, turning a runny stew into a velvety, creamy sauce right before your eyes.

How do I make my rouxs better?

In Chaey’s eyes, making a good roux largely comes down to practice and intuition—but there are a couple tips that can help you get there sooner.

Trust your nose
“You want to cook the flour and the butter until there's no raw flour smell left,” she says, comparing the telltale scent to pancake batter or biscuit dough. If you’re using butter as your fat, you’ll also pick up on the toasty, nutty scent of the milk solids browning (like when making brown butter). Once you reach that point—*notes to self*—lower the heat to avoid burning.

Keep an eye on the color
There are many degrees of doneness in rouxs, all of which get their names from their various hues. White rouxs are used in creamy béchamel sauces, the building block of great macaroni and cheese, and should only be cooked until the flour and fat are incorporated and the raw flour smell dissipates—cook times can vary, but white rouxs generally come together in 3-5 minutes. A light or blonde roux cooks for slightly longer to develop some browning, and is typically reserved for slightly darker foods like turkey gravy. And the dark brown roux, used most often in Cajun food, is cooked until it’s the color of chocolate and ready to lace gumbo with a nutty richness. Word to the wise: Butter will almost certainly burn while making a darker roux, so opt for a fat with a higher smoke point, like vegetable oil, and don't stop stirring until you reach your desired color.

How do I deal with lumps?

Your eventual goal is a glossy, uniform paste that coats the back of a spoon (but doesn’t stick). Lumps can form when the flour packs together, but they’re easy enough to break up. “The best technique is to keep [the mixture] moving constantly,” says Chaey, “and make sure whatever utensil you're using is flexible enough to reach every corner of the pan, because hidden, forgotten pockets of flour will burn.” Starting with a whisk is a good idea—especially a flat whisk, which makes scraping the corners of a pot much easier—but once the bigger clumps are broken up, you can switch to a flexible rubber spatula or wooden spoon.

Still, rouxs can be deceptive. According to Chaey, once you add spices to the roux in her recipe, it will appear to seize up almost instantly, looking a lot like the failed rouxs we’re trying to avoid. Fear not, though—this doesn’t mean your roux is ruined. It’s a ruse! (Sorry.) Once you add that paste to your stock or stew, it will dissolve away just like a Golden Curry block, instantly filling your pan with the creamy finished sauce you’ve worked so hard for.

Roux La-La:

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Japanese Curry With Winter Squash and Mushrooms

If you love instant Japanese curry from a box, a bowl of this soul-warming homemade version packed with seared mushrooms and sweet winter squash will deliver instant nostalgia.
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