You’re standing in the back section of the Produce Department of the grocery store. Before is a display of loose and bagged onions. The labels are pretty easy to understand, they are the color of the vegetable. But what about “sweet” onions? Does it really make a difference between them?
Onions are in the family Allum, which includes all of onions cousins: shallots, garlic, leeks, scallions, and chives. They have been cultivated for at least 7,000 years. They have been used in flavoring cooking for most of that time. They come in varying sizes and pungencies, from mild and subtle to strong and overpowering.
Yellow Onions
These are workhorse onions, used in so many dishes that most people buy ‘em buy the sack. Their flavor and aroma are slight stronger than that of the white onions, but the flavor mellows a lot when cooked. If your recipe just says “onion” with no more description, it probably means a yellow onion.
The terms “sweet,” or “Spanish,” are types of yellow onions. So are Walla Walla and Bermuda varieties.
White Onions
These are slightly milder than yellow onions, they also have a sweeter taste. You find most raw onion applications use white onions, such as on sandwiches, a salad, a bowl of chili or in a salsa. In the store, you’ll see these have a white papery skin, while yellow onions have a more golden hue to the flesh and dark yellow or brown skin. All non-yellow onions will be priced slightly higher. That’s because the bulk of the country’s commercial onion crop is yellow onions.
All onions, regardless of color, have similar nutritional properties. They also have papery skins. What’s more, when you cut a raw onion, sulfuric compounds are released, which can bring tears to your eyes. But just soak them in water for 30 minutes to an hour and it will mellow that pungency a bit. Here’s something you might not know: an onions pungency and cry-inducing fumes only get stronger with age.
Red or Purple Onions
These are usually a little larger than the yellow or white varieties. It also has a sweeter, peppery flavor that holds up well in long-term applications like pickling. They have lower levels of sulfuric compounds and are less likely to cause you to tear up. When cooked, their color (which makes a great dye) fades but the flavor does not.
Can you use them interchangeably? Well, that depends. In most cases, yes you can, although you should take some thought about raw applications where the full force of the onions’ compounds are favored.
Other Varieties Of Onions
Pearl onions are usually white, but there are red and yellow varieties of this miniature onion. Most often you’ll find these in the frozen food section of the store. But there are also pickled and fresh versions.
Cipollini onions are small, sweet, yellow onions that resemble a flying saucer. These are great for roasting into a simple side dish.
Shallots are a different type of onion. They are usually small and have a very subtle flavor that goes well in braised or stewed dishes.
Scallions are another type of onion, often called a Spring or Green onion. These are not just young onions, their defining characteristic is they don’t fully develop a bulb, giving them a stunted-looking root end. They generally grow in bunches and have a mild taste both raw and cooked. The leaves, or green parts, are often used to garnish dishes.
How to select the best onions
It’s tempting when faced with a large display of onions to just grab the nearest bag, put it in the cart and move on. But take a moment to do a quick check to see that the onions are firm, heavy for their size and free of bruises. The skin should be dry and papery and there should not be any sprouts.
Once you’re home, keep your whole onions in a cool and dry spot away from heat sources. If you’re only planning to use part of an onion, save the rest for later in the refrigerator inside an airtight bag or container. It’s even better if your container is glass so the odor won’t linger.
So, while all onions in the Allum family have similar tastes and uses, you can see that they are not necessarily interchangeable. So, you could substitute one for another in a pinch, but it will affect the flavor of your dish. Still, there are plenty of onions to experiment with. So, add onions to your pantry and flavor to your cooking.
I rarely use onions any more. I use shallots, garlic, scallions, and sometimes chives. The onions that are usually sold in grocery stores these days are almost the size of softballs and would take a month to use up.