In America, yellow onions, sometimes called Spanish onions, seem to be the most popular for cooking. In fact, many chefs will say to always choose yellow onions over white onions. So, are yellow onions really superior to white onions?
The answer is no. If you ask a lot of Latino cooks, in fact, they are going to tell you that they prefer white onions. Mexican cookbooks will usually call for white onions. They are considered a bit milder and less pungent than yellow onions.
However, I would be willing to bet that if you did a blind taste test between both types using both raw and cooked preparations, few people would be able to tell the difference. They both end up with a similar texture when cooked, their sugars develop, and much of the pungency is gone. Besides, who says you always want the strongest tasting onion? Nobody said that.
One reason yellow onions are so popular is that they come in 5-pound bags at the supermarket. I never buy my onions in a sack. I want to be able to pick each onion individually, to make sure it is rock hard and has no soft spots or black spots. And this leads me to my particular answer as to whether you should use yellow or white onions for your cooking.
Choose the Freshest, Best-Looking Onions
When you go shopping for onions, the best onions to choose are the best-looking onions. That means that if the white onions look fresher than the yellow ones, you should buy the white. If the white look past their prime, choose the yellow. Of course, you may also want red onions but they are generally used raw and tend to be both sweeter and stronger than white or yellow varieties.
The reason I say the best onion to buy is the best-looking onion is freshness is more important than variety. White and yellow onions are interchangeable in recipes. In fact, although red (or “purple”) onions are usually used raw, you can cook with them too. Just keep in mind that they affect the color and look of your finished dish and although they start out a nice bright and pretty color, they turn dingy and unappetizing looking when cooked.
Notice that I said a lot of general things about the flavors of onions. People often claim that one variety has a stronger or sweeter flavor than the others, but in truth, individual onions vary considerably even within varieties depending on many factors, including, most importantly, where they are grown. Depending on who you’re listening to, white onions are generally milder than yellow onions, or sharper and more pungent. In fact, so many different sources say different things about the two varieties, it begins to appear that people are making stuff up or repeating something they read. You can get a yellow onion that is very strong or a white onion that is very strong. And then, later, you might get a yellow onion that seems quite mild.
One dependable difference between yellow onions and white onions is that white onions are more crisp and firm than yellow onions, and take longer to soften and caramelize.
Regardless, a fresh onion is always better than a less fresh one. If a recipe calls for yellow onions and all you have is white, don’t worry at all. Your dish will be just fine.
How to Choose Onions
Look for clean and firm onions with dry and papery skin. A moist seeming onion is not a good onion. Avoid onions soft spots, black spots or any sort of black powdery substance on them. As well, do not buy onions if they have green stems sprouting from them.
As for storage, I store my onions like potatoes. In a breathable (paper or cloth) sack, tucked away in a dark and cool(ish) place. If you want to store onions for longer, hang them up in a dark cool place using mesh bags or even pantyhose, with the individual onions knotted in separately so they do not rub together. Onions tend to rot at the point of contact.
What About Sweet Onions?
You’ll notice that sweet onions are named according to where they are grown. The most famous sweet onion in America is the Vidalia onion. If it is not grown in Vidalia, Georgia, it really isn’t a Vidalia onion and it may not even be all that sweet. The same thing goes for the other sweet onion varieties generally available, Maui and Walla Walla.
However, don’t believe the widely stated myth that these onions are only sweet because of where they are grown. There are about 20 counties in Georgia, for example, that are ideal for growing Vidalia onions because of the low-sulfur content of the soil and the mild winters, among other factors. However, the same onion grown elsewhere would still be a milder onion. It just wouldn’t be a Vidalia onion.
I’ve noticed the supermarkets have taken to just selling generically named “sweet onions.” It’s anyone’s guess where these are grown and whether they are really all that sweet. However, all sweet onions are bred to be sweet. Just like in Georgia, certain soil and climate conditions bring out this mild sweetness more than others, but anything called a sweet onion should be milder than a yellow or white onion.
Sweet Onion Season
Unlike the yellow or white onions in your produce section, sweet onions are very seasonal. For instance, Vidalia onions are harvested from April to June and Walla Wallas from June to mid-August. This means that if you buy them at the peak of their season, they may be very fresh. But they also have more moisture and do not keep as long.
Vidalia onions are great for using raw, but you can cook with them and substitute them for yellow or white. The same thing goes for other sweet varieties. They are great for caramelizing and they retain their texture better. They are also great for onion rings. When you do cook with them, they may not become as tender as white or yellow onions but this can sometimes be a good thing.