The Most Popular Types Of Onions Explained

The onion is one of the basic building blocks of good food. Innumerable recipes use onions as part of the foundation of their flavor, and sautéing some onions in hot fat is a surefire way to make your kitchen smell amazing.

The versatility of the humble onion is hard for any other ingredient to match. Depending on how you treat them, onions can be sharp and pungent, sweet and sugary, or simply savory. But it's not just how you cook them, either; there are many different types of onions, and each one brings its special attributes to a dish. You could say that, like ogres, onions have layers.

If you've ever been overwhelmed by the onion selection at your local grocery store or thought to yourself, "what even is a shallot, anyway?" this guide is for you. We break down the most popular types of onions (and onion-like alliums), tell you what they taste like, and briefly explain what applications they're best for.

Red onions are similar to their yellow cousins in size, shape, and flavor, but they're a deep reddish-purple instead of pale yellow. You may find that they taste a little less sharp when raw than yellow onions do, and chefs and consumers alike tend to prefer them for raw applications like sandwiches and salads (via Specialty Produce). You can also pickle them, which gives them a beautiful pink hue and makes them a perfect topping for a variety of dishes like salads, burgers, and tacos.

According to the National Library of Medicine, red onions are purple because they contain anthocyanins, which, in addition to being pigments, are antioxidants that can be beneficial to your health. If you're wondering why they're called red onions when they're purple, Allrecipes posits a few different possible explanations. It could be that the name developed before we had many names for colors when the word "red" had a broader definition than it does today. Another potential source of the name is that red onions can be used to make red dye. But perhaps the simplest answer is that some red onions are red, as their color varies depending on growing conditions.

The term "sweet onion" is a catch-all for several different regional onion varieties, including Georgia's Vidalia and Hawaii's Maui. The trait they all share is that they are low in sulfur, which is the compound that makes standard onion varieties pungent. Per Fine Cooking, the lack of sulfur is due to the soil conditions in the regions where they are grown.

Sweet onions are more delicate and have a shorter shelf life than storage onions. For that reason, they are traditionally only available for part of the year, though that is changing. Most varieties are harvested in the spring or summer.

Sweet onions are great for raw onion garnishes, as they lack the astringency of other types of onions. They also respond well to cooking methods that enhance their inherent sweetness. If you want a dish that treats sweet onion as a centerpiece, try making an onion sandwich with raw slices of sweet onion on some bread lathered with your favorite condiments.

Okay, leeks aren't technically onions, but they're an allium with an oniony flavor, so we think they belong in this article (via MasterClass). They taste similar to regular bulb onions, but they're milder, sweeter, and less pungent. Leeks kind of resemble overgrown scallions, with dark green tops fading into white stalks. The top leaves are often thrown out, as they're quite tough and fibrous. However, with some careful cooking, they can be transformed into something tasty, as both The Guardian and Taste point out.

The white and light green parts of a leek are quite versatile. You can use them as a flavoring component of various dishes or serve them as a vegetable in their own right. One thing to pay attention to when preparing leeks, though, is that they're usually filled with dirt when you buy them, which leads to an unpleasant eating experience if they're not properly cleaned. Read our guide on how to clean leeks to make sure you don't actually serve any sand.

Shallots aren't exactly onions, but, per Bon Appétit, they're in the same family. They taste similar to onions and can be used as a substitute in most recipes, although they bring their own special flavor to the party. They look a lot like small red onions, though they're shaped slightly different and they come bunched together in a manner that's more reminiscent of garlic.

Taste-wise, shallots are like sweeter, gentler onions. They're great for when you want that onion-esque flavor in a dish but don't want the sharpness of onions to overwhelm the other ingredients. For example, our shallot mignonette recipe adds just the right amount of brightness to raw oysters without upstaging the star of the show. If you made it with regular yellow onion, it might distract from the delicate flavor of the shellfish.

Shallots are also great in cooked applications. Since they're relatively small, they can even be cooked whole, which enhances their sweetness.

Although cipollini onions share pearl onions' diminutive size, they are not the same thing at all. As The Kitchn explains, cipollinis are a special onion variety with a higher sugar content than the average onion. They're originally Italian but are now pretty easy to find in U.S. grocery stores. Instead of being perfectly spherical, they have a sort of thick disk shape. Color-wise, cipollinis are similar to standard yellow onions.

Fine Cooking says the classic way to serve cipollinis is to cook them whole and dress them in Italian-style sweet and sour sauce, but they sing in any application that calls for a sweeter-than-average onion. You can roast them, braise them, put them in a stew, or caramelize them to make the most candy-like onion topping you've ever tasted. Like pearl onions, they can be kind of annoying to peel, and it's best to blanch them before removing the outer layers.