Why You Should Freeze Caramelized Onions, and 3 Ways to Do It

Tips from The Kitchn

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Did you know you can actually freeze caramelized onions? Yup, those flavor-packed little strands of sweet onion freeze beautifully, so why not make a bigger batch the next time you're caramelizing some anyway or find yourself with a big bag of onions to use up. Here's how we do it!

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Why freeze caramelized onions?

We love the nutty, sweet flavor of caramelized onions in just about any dish, but the actual caramelizing process can take too long for a weeknight meal — there really isn't a shortcut to making good caramelized onions. Since you can just as easily caramelize one onion as five or six of them, we make a big batch of caramelized onions at once, and then freeze what we won't use in a few days to have on-hand for quick meals.

Caramelized onions also cook down a lot, so it's worth it to make a big a batch as you can. We've found that 4 big pomegranate-sized onions caramelize into just a scant 2 cups, so go big!

As long as they don't start to develop freezer burn, frozen caramelized onions will keep for several months. Here are our three favorite ways to freeze the onions, give them a try!

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3 Ways to Freeze Caramelized Onions

1. Ice Cube Trays

Portion out the onions into ice cube trays and don't be afraid to pack them in. Once they're frozen solid, we pop them out of the tray or nudge them out with a table knife and keep them frozen in a sealed container. The smaller portions make it easy to use exactly what we need, plus the onions thaw more quickly in the pan.

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2. Muffin Tins

Regular muffin tins can hold about a 1/2 cup of caramelized onions in each well for bigger projects like pasta sauces or braises. To make it easier to pop out the frozen portions from metal tins, line the wells with plastic wrap first. If you choose not to do this, you can let the muffin tin thaw briefly on the container before you pop them out with a table knife (be careful not to scratch your muffin tin though). Keep these little discs frozen in a sealed container or plastic bag.

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3. Freezer Bag

Not sure how much caramelized onion you'll use at one time? Just throw them all into a freezer bag that's big enough for it to spread into an even, thin layer (keep it to no more than 1/2-inch thick). When you need caramelized onions, just break off a frozen chunk straight from the bag!

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Using Frozen Caramelized Onions

Now that you've stashed away some yummy caramelized onions, it's easy to quickly inject food with a big shot of flavor. Throw it into a pot of soup, into a braise or stew, use it as a filling for an omelet, or just add to your next sandwich or burger — even if you're vegetarian or vegan, these onions will add a ton of satisfying, deep flavors without the use of meat or cheese.

Updated from a post originally published in April 2009.

(Image credits: Christine Gallary; Emma Christensen)