10 Things You Didn’t Know About…Cooking with Onions
Onions have always been a sort of mystery to me. How did such an unassuming and (let’s face it) fairly ugly bulb become the one item in the produce section that you’re most likely to haul home week after week, given that they’re essentially the starting point for any number of recipes, from soups and stews to sauces, casseroles and skillet dinners of all stripes? Not to mention, onions are a pain to work with — downright hostile, to boot. (At least your Idaho russets won’t make you cry.)
Simmering them in butter or oil inevitably subdues them; their juicy, stinging scent melts away into something sweeter, seductive — the very basis of the aroma that invariably gets a “Mmmm … something smells good” from whoever walks in the door. In the pan, they go pale, then translucent, almost ghostly, before seeming to disappear entirely. What they leave behind is a kind of magic. A hint of sweetness, yes, but something more, something deeper.
New research into the science of taste is telling us more about why onions matter so much when it comes to cooking (see item #5 below). It’s just one of the surprising things you learn when you stop to get to know one of the most often used (but overlooked) vegetables in our kitchens …
Onions are closely related to garlic, chives and leeks, all of which (scientifically speaking) are members of the lily family.
Although there are dozens of different types of onions, the three you’ll encounter most at the store are yellow, white and red (a.k.a. purple). Yellows are typically the sweetest when cooked — but also the most pungent. They’re a good all-purpose onion, forming the base for everything from soups to pasta sauces. White onions are milder and less sweet (often preferred in, say, Mexican cooking), and reds are milder still (which makes them a good raw onion for things like salads and as a garnish for burgers).
You can take some of the bite out of raw onions by soaking the slices in water for a few minutes then patting them dry. An even dreamier garnish? These eminently easy pickled red onions.
How to pick a good onion? The firmer the better. Also look for onions that have dry, papery skins. Avoid any that feel too soft, have sprouted, or have sooty blackish spots (a sign of mold).
A couple years ago, Japanese researchers announced the discovery of a new “flavorless flavor” they call kokumi. Essentially, kokumi foods act as mega-boosters for our perception of other flavors, such as salty or sweet. Onions are thought to be one of these foods.
Onions, however, don’t want to be eaten. That’s why they evolved a knack for sucking up sulfur from the soil, which proved to be a great deterrent to hungry foragers — until humans learned to cook them.
Cutting an onion is the perfect way to activate its arsenal of chemical defenses. A veritable cloud of volatile sulfurous compounds attack the nerve endings in your eyes and nose, according to food science writer Harold McGee, where they break down into tiny amounts of hydrogen sulfide, sulfur dioxide and (ouch!) sulfuric acid — which is why your onion tears sting.
You could probably fill a book with all the old wives’ tales about how not to cry when you cut an onion (chew a piece of bread, for example, or suck a lemon — which seems to trade one painful experience for another). Professional cooks tend to agree that the best defense is simply to use a sharp knife (which minimizes cutting time). You can also soak your onion in a cold-water bath for 15 – 30 minutes before cutting.
If cold onions make for fewer tears, then why not just store them in the fridge? They tend to suck moisture out of other produce (especially potatoes), which can cause mutual spoilage. It’s best to store them in a cool, dry place, like the bottom of your pantry.
Vidalia Sweet Onions are, perhaps, the world’s best-known name-brand onion, and like many an agricultural success story, they were developed by accident. Georgia farmers hit hard by the Great Depression were looking for a cash crop that might be more lucrative than corn or cotton, so they decided to try their hand at onions. What grew, however, wasn’t a typical onion; central Georgia’s sandy soil doesn’t contain a lot of sulfur, so the onions were much sweeter. Today, Vidalia Sweet Onions are the official state vegetable of Georgia.