One of the most important ingredients in all of the culinary arts, garlic nevertheless seems to defy or transcend, attempts to define it in any but the most literal of terms. In that sense, then, garlic, like onions, shallots, and leeks, is a member of the lily family.
Intensely and uniquely flavorful and aromatic, garlic is used in virtually every cuisine in the world, including nearly every form of Asian, European, African, Latin American and North American cooking.
Garlic grows underground in the form of a bulb, from which long green shoots emerge from the top while its roots extend downward.
The garlic bulb is covered in a papery skin which is inedible. The bulb, or head, is in turn comprised of individual sections called cloves. The cloves are themselves enclosed in the same paper like skin, and the pale yellowish flesh within is the part of the garlic that is used in cooking.
Garlic has a powerful, pungent flavor when eaten raw. For that reason, it's customary to cook garlic in some way before eating it, which mellows the flavor considerably. Garlic is generally used as a flavoring ingredient in recipes rather than as the main ingredient itself, although roasted garlic can be eaten as a spread or condiment.
Cooking with Garlic
Garlic can be added to recipes that are sautéed, baked, roasted, braised; added to soups, sauces, marinades, spice rubs, stir-frys; minced and used in sausages, meatballs, and other ground meat preparations.
Like its cousin the onion, garlic also produces a sulphur-based enzyme which is released when it's cut up. The chemical is stored in tiny cells within the flesh of the garlic. When it's sliced or crushed or grated, those cells are ruptured, which releases the pungent compound within.
Unlike onions, which produce this enzyme in a form that allows it to become airborne, which is why it irritates your eyes when you slice them, the compound in garlic is only transferred via direct contact.
But that means you can get it on your fingers and from there to your eyes.
Crucially, however, the more you slice, pound, grate or chop your garlic, the more of that compound, called allicin, is released. Therefore, if you grate your garlic using the small holes on a box grater, puree it in a food processor, your garlic will emit much more heat than if it were sliced. This is useful to keep in mind when you're thinking of saving time by tossing those garlic cloves into the Cuisinart.
Therefore, if for some reason you want to mince garlic without a knife, pressing the cloves with the tines of a fork will produce better results than a grater or food processor.
There is probably no end to the uses and potential uses of garlic in the culinary arts. The green shoots of the garlic plant can also be eaten and have a garlicky flavor, though much less potent than in the cloves themselves.
The word spice indicates any other item, including roots, bark, seeds and so on, but specifically in the dried form. Garlic really doesn't fit either one of those categories.
So it's probably most accurate to call garlic a vegetable, even though it's hardly ever eaten on its own. In this sense, garlic is most similar to onions and shallots, although ultimately garlic belongs in a category all its own.
Also see: Quiz: Is it an Herb or a Spice?