Real Food Encyclopedia | Onions

The onion: the flavor cornerstone of just about every cuisine on this planet.

But it seems like the poor, homely onion is always the bridesmaid, never the bride. But without it, many of our favorite dishes would be boring, indeed.

Fun Facts about Onions:

  • By law, the trademarked “Vidalia” onion, a sweet variety, is grown only in parts of Georgia. Growing of the cultivar started in the 1930s in Vidalia, Georgia.
  • According to food scientist Harold McGee, onions take up sulfur from the soil to produce the various compounds that result in their distinctive peppery, pungent flavor. These compounds are stored in cells that, when ruptured (due to cutting or chewing), release their strong-smelling (and eye-irritating) molecules.

What to Look for When Buying Onions

For dry onions, avoid any mushy or brown spots, as these can cause the entire onion to rot quickly. Also choose onions that feel heavy for their size and are not sprouting. For fresh spring onions, look for glossy skin and, if their greens are still attached, perky, fresh green tops.

Onions are divided into four major types based on their color and flavor: red, yellow, white and sweet. Red, yellow and white types are available as both spring and dry onions.

  • Red onions:(aka purple onions): have reddish to purple skin and red-tinged interiors. They tend to be sweeter than either white or yellow onions and are often quite large.
  • White onions: (aka Bermuda onions) are more pungent than their yellow or red cousins. They are also a bit more tender than the other types.
  • Yellow onions: (aka Spanish onions) are the most common types seen in grocery stores. They have yellowish, papery skin and a creamy white interior. Yellow onions are great all-purpose onions.
  • Sweet onions: are usually specially grown in certain parts of the country that have soil and climate that produces a mild, sweet type of onion. Examples are Vidalia and Walla Walla onions. They are far less sharp than the other types of onions.

Sustainability of Onions

Onions are a pretty water-intensive commercial crop, which makes them less than ideal if sourced from drought-impacted areas. As an aside: onions that have been exposed to environmental stresses like drought tend to be far more pungent. The good news is that you should be able to find onions — both the dry and spring types, depending on season — at just about any local farmers’ market, year-round.

Pesticides and Onions

Onions are also very susceptible to nematodes and other insect pests and to a number of different fungi that can cause the bulbs to rot. In addition, they don’t compete well with weeds. All of this adds up to a lot of likely pesticide use in conventionally grown onions, which make an appearance on the Environmental Working Group’s Shopper’s Guide to Pesticides in Produce. If all of this leaves you concerned, choose certified organic or locally grown onions and talk to your local farmer about his or her growing practices.

Onion Seasonality

Fresh market onions (aka, “Spring” and “green” onions) are available from March through August. Dry onions are available year-round, as they can be stored for long periods of time in the right conditions.

Onions and Geography

In the US, California, Washington State, Oregon and Idaho grow the most onions.

Allium cepa, the bulb onion, is in the Amaryllidaceae (Amaryllis) family, and counts as its cousins many lovely garden plants, including the eponymous amaryllis, along with daffodils, snowdrops, tuberose and a number of ornamental lilies. Aside from the bulbing onion, by far the most common species of Allium grown, genus also includes shallots, garlic, ramps and chives.

Bulbing onions are commonly divided into two different types:

  • “Dry” onions: harvested when their tops flop over. They are usually stored for longer use over the fall and winter months. Dry onions tend to have less water content and are “hotter” than green onions. They account for the majority of US onion production. Dry onions have to be dried (or “cured”) for a period of time to prevent rotting.
  • Green (aka “spring”) onions: harvested while the tops are still green. These onions are sometimes pulled before the bulbs have fully formed, to capitalize on their edible green tops. Later in the season, they are sold as “fresh market onions” with larger bulbs. Fresh market onions have higher water content and tend to be milder than dry onions.

Onions can be planted as “sets” (seedlings) or can be grown from seed. Globally, China, India, the US, Iran and Russia are the top dry onion growers. Onions are pretty easy to grow at home on your counter — here’s a quick tutorial on how to grow onions from discarded onion bottoms.

Eating Onions

Storing Onions

Stored in a cool, dry place, dry onions keep for many, many months. (Exposing them to light hastens sprouting, which can mean quicker rotting.) Spring onions should be used within a week. Store them in the crisper drawer of your refrigerator.

Cooking with Onions

Onions are the true workhorses of the kitchen and are absolutely vital to most cuisines around the world. They are combined with carrots and celery as a flavor base in French and Italian cuisines (called mirepoix in French and soffritto in Italian) and with bell pepper and garlic (and other aromatics, depending on the cuisine) to make the Spanish, Caribbean and Portuguese flavor base sofrito. Used raw, they add a crunchy, potent punch to salads, sandwiches and dips. Cooked, they become meaty, rich-flavored and full of umami — especially if they are cooked low and slow until their sugars caramelize. Here’s how to caramelize onions. In India, onions are turned into pungent chutneys, in the US they are combined with sour cream to make the world’s best dip and in Mexico they are pickled and added to tacos.

One of our favorite onion dishes is the Alsace onion tart, made with lots of caramelized onions and heavy cream, and the other is French Onion Soup, which has a pretty interesting history all its own. Here’s a great roundup of 40 onion-centric recipes from Saveur.

All that sounds great, but what you really want to know is how to stop crying when you chop onions. There are a few different methods, ranging from the absurd to the sort-of plausible. Here is a highly scientific test of a few of these no-cry methods, with the winners being:

  • Wear goggles (they make silly onion goggles, but regular swim goggles will do)
  • Cut the onion under a vented hood
  • Freeze the onion for a few minutes before chopping

Another pro tip — to get the onion-y funk off of your hands after you’ve chopped one up, rub your hands on something made out of stainless steel.

Preserving Onions

Onions can be turned into jam (like this bacon and onion jam or all of these onion jams). You can freeze fresh onions, or even smarter, freeze caramelized onions.

Onion Nutrition

Onions are low in calories and high in fiber, and they are loaded with Vitamin C. They’re also pretty good sources of Vitamin B6, folate, potassium and manganese. The pungent bulbs have been used since antiquity all over the world for a number of different ailments and recent research is shoring up some of the ancient beliefs about the physical benefits of onions (although they won’t protect you from snakebites. Probably.).