A step-by-step guide to freezing raw and cooked onions, including storage tips and the best recipes for using them

Lauren Salkeld
April 13, 2020
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How many times have you tossed a quarter of an onion in the crisper drawer only to let it languish for a week or more before finally giving in and throwing it out? It happens. But it's also a waste of food and money and can easily be avoided with a little help from the freezer. Yes, that's right: Onions can be frozen, which means you can save any extras or get a jump-start on dinner prep by chopping and freezing onions in advance. For everything you need to know about freezing onions, plus how to thaw and use them, read on.

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How to Freeze Raw Onions

While it's possible to freeze whole onions, they're not easy to use, or to fit in the freezer. A far better approach is to freeze chopped or sliced onions, which will keep for up to six months. You can use a food processor to speed up the chopping or slicing, but avoid super-small pieces, which can turn mushy in the freezing and thawing process. (Find out How to Freeze More Fruits and Vegetables here.)

Sliced and diced onions have a strong odor, so using heavy-duty freezer bags is key, and be sure to store them away from any foods that might absorb odors. If you want to be extra cautious, double-bag them. Once the chopped or sliced onions are in the bag, squeeze out as much air as possible and flatten the bags for quicker freezing and defrosting and so they lie flat in the freezer. And don't forget to label and date the bag.

If you're a plan-ahead kind of cook, chop and slice onions and freeze them in quantities you'll find useful, like 1-cup portions, for example. That way, you only defrost what you need right away.

Freezing Cooked Onions

Another way to save time is to sauté or caramelize onions in large batches and freeze smaller portions for later use. This is especially handy for caramelized onions, which are particularly time-consuming but add tons of flavor to food. Be sure to let the cooked onions fully cool, then store in airtight freezer bags for up to three months. To freeze small, easy-to-use amounts, line the cups of a muffin tin with plastic wrap, pack with cooled cooked onions and freeze until solid. Use the plastic wrap to pop out the onions, then transfer to a freezer bag for longer-term storage. Let the cooked onions thaw in the refrigerator overnight before adding to soups, pastas and braises, or using as a burger topping.

How to Thaw Frozen Onions

While onions defrost quickly, to speed up the process you can submerge a bag of frozen onions in a bowl of cold water. Since onions are mostly chopped or sliced thinly, they can also be used straight from the freezer without any defrosting in most circumstances.

Best Ways to Use Frozen Onions

Previously frozen onions aren't as crisp as fresh ones, so they're best used in cooked dishes, especially ones that rely more on their taste than their texture—think soups, stews, casseroles, sautés and dishes made with ground meat. They also release more water than fresh onions, which means you may need to cook them a bit longer and they're not ideal for caramelizing.

Freezing Other Alliums

Onion relatives, including shallots, garlic, leeks and scallions, can all be frozen using the same method. If you wash the leeks and scallions, which you should, be sure to thoroughly dry them before freezing.