Red Onion vs. Yellow Onion: An Expert Explains the Difference

Though they're often called "humble"—probably because they're affordable, readily available, and grown in the ground—onions deserve serious bragging rights. Whether raw, pickled, sautéed, roasted, or fried they're essential to countless dishes from just about every cuisine. I am never without onions in my kitchen.

However, when it comes to choosing a type of onion for a particular job, as I confessed in my article about yellow onions vs. white onions, I often just go with whatever I have on hand. Frequently, what I have on hand are red onions, because they're just so darn pretty.

To find out whether—and when—it's a mistake to willy-nilly swap red onions for yellow onions, I reached out to Jay Weinstein, chef-instructor of Plant-Based Culinary Arts at the Institute of Culinary Education to learn more.

Weinstein confirmed that it's usually OK to swap yellow onions for red onions and vice versa, but there are some cases in which a red onion is really the allium for the job. Here's everything you need to know. 

What Is the Difference Between Red and Yellow Onions?

The most obvious difference between red and yellow onions is their color. Red onions get their reddish-purple color from anthocyanins, a compound that gives a red, purple, or blue hue to blueberries, purple cauliflower, eggplant, and more. These anthocyanins not only make foods look pretty—they are antioxidants that have also been tied to potential health benefits such as reducing the risk of heart disease and cancer, according to the Cleveland Clinic. All types of onions have tons of health benefits, but if you're looking for that specific anthocyanin boost, red onions are the way to go. 

What Are the Best Uses for Red Onions vs. Yellow Onions?

"Red onions’ superpower is their eye appeal," says Weinstein. Thanks to their gorgeous color, red onions "provide dramatic presentation opportunities," as Weinstein puts it, so reach for them when you want to add a pretty pop of color to pizza or salads.

"Pity the Greek salad garnished with yellow or white onions," says Weinstein. "The color is part of the dish’s identity.

Weinstein also loves the "instant drama" that pickled red onions add to a dish. "Introduce an acid to the red onions, and their purple color blossoms into brilliant magenta," he says. "Pickled red onions vitalize color-deficient foods."

Beyond their color differences, red and yellow onions have some different culinary attributes as well that make red onions superior for certain dishes. "Spicier than yellow onions when raw, red onions add a kick to salsas, sandwiches, and salads," Weinstein says. "They acquire silky, jammy textures on the grill or when roasted in the oven. That smooth interior makes them more luxurious than their golden cousins for antipasti and barbecue plates."

Does It Really Matter Which You Use?

If you are cooking them, in almost all cases red onions, yellow onions, and white onions can be swapped for one another. "Flavor-wise, the cooked dishes will taste virtually the same using red, yellow, or white onion," says Weinstein. "Red and yellow onions are interchangeable in dishes where the onions won’t be seen, such as chili or brown sauce," he adds.

If you're using the onions raw, you might notice some flavor differences between red and yellow onions. "Raw, red is the spiciest followed by white, then yellow," says Weinstein, adding that you should choose which kind to use based on how much spiciness the dish you're making requires.

"For raw onion dishes, choose onions that fulfill a need," he says. "If it needs color, or would benefit from a neutral presentation, buy accordingly." Weinstein also shares this pro tip: If you want the color of red onions but not the burn, slice them thinly and soak them in cold water for about an hour to take the bite out of them. 

The Takeaway

For most cooked dishes, red and yellow onions are interchangeable, so feel free to use what you have on hand. But if you're looking for a gorgeous color—plus the antioxidant anthocyanins that come with that color—reach for spicy red onions and give your dish that dash of drama.