ALL ABOUT ALLIUMS

Onions are but one member of the vast family, Allium.

Q: I would love some direction about these vegetables. Does garlic get bitter if you cook it too long? What is the difference between all the onions available? How to stop your eyes from tearing when you cut them up? . . . And what can you do with leeks? Grill? Put in soup? . . . What is the difference between scallions and green onions? Nancy, Chicago.

A: Nancy: Let’s work backwards, of a sort. “Scallions” or “green” (sometimes also called “spring”) onions are the same thing, different name. Some Australians and Québécois even call what we call a “scallion,” a “shallot.” Green onions are truly “green,” that is, they are immature, not fully grown onions.

Leeks, like onions and garlic, another member of the Allium genus, resemble very large scallions. Their white section is generally milder in flavor and aroma than either the onion or the shallot. The most famous dish made with leeks is the potato-based soup Vichyssoise (interestingly, so-named, an American recipe, invented by a French-born chef at the Ritz-Carlton Hotel in New York City).

By and large, the common leek is too thick to grill successfully or profitably, although thinner (less mature) specimens might work. At Asian produce markets, you might find an allium thicker than a scallion and thinner than a leek. I’ve enjoyed grilling them. They go by different names such as “large green onion” or dàcōng).

When cutting up any allium, but especially onions, I learned a trick that helps me “cry” less. Place a burning candle on either side of the cutting board. The flames eat up the volatilized sulfuric compounds that irritate and burn the cook’s eyes. At least, it works for BSJ.

So many onions from which to choose the proper one! The most common, yellow onions, are plentiful and all-purpose—not as terrific raw as other onions, but passable thus, and always sweet when cooked down or for a long time. Here’s how to cut up one and a recipe in which to use it. (Here’s a video in which I show you how to cut up an onion.)

Here in Colorado, white onions are popular in Mexican cooking, also raw either chopped or sliced. They’ve got more “onion-y” flavor and can be quite pungent, but they don’t hold up in long cooking the way that yellows do. Most people think the red (also called “Bermuda” or “purple”) onion to be delicious raw and indeed that’s how you’ll often find it (atop a burger patty, for example, or in a Greek salad). They lose their crimson on cooking, so keep that in mind. Some folks think that red onions have gotten stronger and punchier over the last decade. I’ve no research that I can find (nor have done) to back up that claim.

Sweet onions, as their name says, are much less pungent than other regularly available onions of whatever color. The two most famous monikers are Walla Walla (from Washington State) and Vidalia (from the State of Georgia). In Colorado, we grow a delicious sweet onion called the “Colorado Sweet,” thought it may be difficult to find. All sweet onions have a higher sugar content and more water than other alliums, can easily be eaten raw, and turn even sweeter on long cooking.

The shallot is a sort of cross between a yellow and a red onion, but much smaller than either, and it has lobes like the garlic bulb’s “cloves,” though they are much larger. Its delicate flavor and size lends it suitable for use raw in things such as mignonette (for raw shellfish) or adding just a whisper of allium flavor to quick sautés and the like.

The chive is basically the hollow-stemmed “leaf” of a very small onion; its blossom, if you can find it still attached, is even better eating or flavoring.

Finally, garlic, about which I have written much and eaten even more. Yes, garlic gets bitter if you severely brown it or burn it (not, as your question suggests, if “you cook it too long,” but only in certain ways of cooking). In truth, it gets mellower, sweeter, nuttier when cooked at length, especially in liquids such as stews or braises.

You’ll hear from many people (or read widely) that the small green sprouts that emerge from stored cloves of garlic are themselves bitter and ought to be excised from each clove before cooking. I have not found that necessary; the sprouts, in fact, are not bitter.

Just be careful when quickly cooking garlic over direct heat such as in a small amount of fat in a skillet or when “sweating” onions. Garlic is low in both water and fructose so it burns easily.

Moreover, of most interest to the scientist in me (such as he is), is the compound allicin which gives garlic its garlickiness, its pungency, piquancy and aroma. Allicin is formed when the cells in a raw garlic clove are broken (sliced, minced, crushed, etc.) and when alliin and alliinase—two compounds separated within garlic—now are allowed to combine.

Allicin is highly scorchable and, when burnt, is very bitter. So, the byword is “Do not excessively brown or burn raw garlic,” especially over high or medium-high heat.