How to Buy an Onion
Onions are food for grown-ups: kids hate them but most adults would simply find the world less delicious without them. Onions are the base of almost every cuisine as the dominant ingredient in a rustic soffritto (onion, garlic and carrot), a delicate mirepoix (onion, celery, carrot), a Creole holy trinity (onion, celery, bell peppers) and an Indian wet trinity (onion, garlic, ginger).
But for a quotidian vegetable, onions are tricky to buy. Most grocers stock at least six types, Fairway offers about a dozen, and depending on the season, the Greenmarkets can have even more. Which you choose depends upon what you’re cooking.
The Big Four
- Yellow: This is what most cooks reach for when a recipe says simply “onion.” It’s full-flavored, versatile, turns golden brown when sautéed, and is the best choice for onion soup. It’s also among the highest in sulfuric acid, the stuff that makes you cry, making it too sharp to eat raw.
- Spanish: These look like extra-large yellow onions but they’re not only bigger, they’re sweeter. But not sweet enough to eat raw. They’re good in a pilaf and are ideal for onion rings.
- White: With some as large as a softball, white onions become sweet when cooked, making them a great choice for Mexican dishes.
- Red: Red onions come in sizes from small to huge and with a fresh, spicy taste are eaten raw as in salad and also grill well.
Buy First. Cry Later.
Most grocers sell onions loose in bins, separated by type. Choose each to be firm and heavy for its size. Next, smell it. Nothing? You might sniff a peach or melon looking for its perfume, but an onion should have no scent. Finally, make sure it has an unblemished papery outer skin and a dry neck. If it’s begun to sprout, put it back.
Cut an onion and a fume of mild sulfuric acid can irritate your eyes. Some insist you can limit irritation by avoiding the root end where most of the sulfuric acid is, or chilling it for 30 minutes before cutting. I've given up trying to avoid the tears and instead just cut as fast as I can using my sharpest knife.
Finally, don't store your onions in the refrigerator. I keep a ceramic bowl on my counter where I hold my onions, garlic and shallots at room temperature and out of the sun. They last for several weeks this way.
The Extended Onion Family
- Scallions: Also called green onions, scallions are eaten both raw and cooked. Look for a firm, white bulb and bright green stalks.
- Shallots: A species of their own, shallots have a mild, onion-garlic flavor and are often substituted for onions, eaten cooked or raw.
- Pearl onions: These miniatures are usually boiled whole and used in stews and stir-fries. Yellow pearls have more flavor than the white, and the red are mild enough to eat raw in a salad when peeled and marinated in vinaigrette. Frozen ones are often a terrific alternative with good flavor and none of the work.
- Leeks: With a white bulb and long green stalk, leeks are almost always eaten cooked. Since leeks are grown in sand, clean them very carefully or else you’ll add grit to your recipe.
- Sweet onions: Vidalia. Walla Walla. Texas Sweet. Maui. Sweet onions are regional prides with a mild flavor that is best eaten raw, as on a burger, or as the centerpiece of a recipe like onion pie.
- Cipolline: With a distinctive oval shape, cipollines are an Italian onion now also grown in the U.S. They become sweet when cooked and hold their shape when grilled.
- Ramps: Come spring, start stalking your greengrocer and markets for these and lucky the cook who finds them. Ramps are wild onions that look like bulbous scallions and have a pungent and savory onion-garlic taste. Eaten both raw and cooked, these in-demand delicacies have a very short season.