Save money, cut down on food waste, and extract more flavor from your produce by keeping and using these precious scraps.

By Margaret Eby
March 20, 2020
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I don’t have a lot of room in my kitchen, and I try to be judicious about allocating space to things. That means, in normal times, that I try to limit the vegetables in my fridge to what I know I can eat before they go bad. But no matter what I’m cooking, I always have onions and garlic on hand. Onions and garlic are both workhorses in the kitchen. There’s almost no dish I don’t use one or the other or both in, from red lentil dal to roasted chicken. But for years, I hadn’t been using them to their full potential, because I was (not surprisingly) throwing away their skins after I peeled them.

It turns out that there’s a ton of flavor in the papery outer layers of onions, and same for garlic. The skins on both alliums are unpleasant to eat, as well as possibly a choking hazard, but they’re absolutely wonderful for infusing flavor into soups, sauces, and stock. If, for example, you’re making a pot of braised short ribs or pork shoulder, you can cut an onion in half and throw it in, skin and all, or cut a head of garlic in half and put it in the pot without extracting the cloves from their shells. Once the meat is done cooking, just fish the onions and garlic out. You can peel off the skins, cut up the vegetables and put them back in, if you want. At that point, the long-simmered garlic gloves will have the consistency of roasted garlic, and you can spread them on bread. Or you can compost the onions and garlic at that point—after a long slow braise, they'll have given up their flavor.

Matthew Leete / Getty Images

Even if braising is not in your future, save those onion and garlic skins the next time you remove them for chopping or mincing, put them in a Ziplock bag, and stash it in the freezer. When it’s full, use those scraps to make stock. You can add in chicken or beef bones to make a rich, umami-packed homemade meat stock, something that can be the backbone of any soup or braised dish you make. 

If you don’t have bones or don’t eat meat, no fear—the onion and garlic skins alone make a wonderful, flavorful vegetable stock. Just put them in a pot, cover them with water to about an inch short of the top of the pot, and simmer them gently for several hours before straining them out and saving the liquid. I often add bay leaves, peppercorns, dried mushrooms and a piece of kombu, a Japanese seaweed, to the pot of the skins for extra flavor, but it works perfectly fine without it. I freeze the stock in ziplock bags stacked flat on on a sheet pan, and then store them vertically in the freezer for easy access whenever I need them. (Though I’ve also been a recent convert to Souper Cubes, a kind of mega ice cube tray that allows you to freeze cup-sized portions of stock into blocks.)

Whatever you do, don’t throw away those garlic and onion skins. Hang on to them and get all the flavor you can from your groceries—it’s good for the environment, your tastebuds, and your wallet.