Onions are an essential ingredient in most dishes. From soups and stews to steaks and even burgers and pizza, these bulbs go incredibly well with almost everything. While they have a long shelf life, sometimes you end up with more than you can consume before they start to go bad and one of the best things to preserve them is by learning how to freeze onions.
That’s when knowing how to freeze onions comes in handy. Luckily, it only takes a few minutes and everyone can easily learn how to do it.
To freeze onions, you have to prepare them, cut them into pieces, flash-freeze them individually for more convenient storage, and then transfer them to freezer-safe bags or containers before putting them back in the freezer.
Read on if you want to know more about the different ways you can freeze these bulbs for later use!
Ingredients and Supplies You’re Going to Need
To freeze onions you’re just going to need a few things you can easily find in your kitchen:
- 5 pounds (2 kg) of onions
- Sharp knife
- Cutting board
- Baking sheet
- Parchment paper
- Freezer bag or freezer-safe container (Don’t use zip-lock sandwich bags because they risk leaking onion odor into your freezer. Use thicker freezer bags instead.)
- Permanent marker
Choosing the best onions for freezing is easy, but it’s also very important to ensure the best results after freezing. So, avoid those that feel soft or squishy when you press them with your fingers. If you see any green sprouts coming from the neck of the onions, it means that they’ve been kept in storage for too long to be usable.
Go for those bulbs that are firm, heavy for their size, and bruise- and blemish-free.
If you’re growing your own onions, the best time for harvesting them is by midsummer, when the bulbs start to fatten up. You can harvest individual onions as you need them, or do them all at once and freeze them for later.
By the end of summer, and the beginning of fall, the plant will stop growing. You’re going to notice that the leaves at the “neck” of the onion start to look droopy. This means that your onions should be harvested soon.
After harvesting them, you have to cure your onions. This involves fully drying the outer layer of the skin. If the weather is dry and there’s no danger of frost, laid the plants out under the sun right in the garden for a day or two. However, if the weather is wet or frost is possible, move them to a covered area.
Spread them out in a single layer on racks, layers of newspaper, mesh bags, or any other place that’s dry and breezy. Take care not to bump the onions when you’re handling them because they’re delicate and prone to bruising.
As the onions cure, their necks will start to wither, and their skins will dry and tighten around the bulbs. Once the stems no longer contain any moisture, trim the roots and the leaves with a pair of scissors.
After that, you can either store them in a dark, cool place or freeze them right away!
How to Freeze Fresh Onions
If you’ve been freezing vegetables for a while now, then you probably know that they often have to undergo a process called “blanching” to help preserve their texture and flavor better. However, that’s not the case with onions, which means that the freezing process is even simpler!
Peel the outer, papery skin of the onions and scrub the bulbs clean with a vegetable brush under cool running water. Use a sharp knife to chop the onions. Start by cutting off the top ½-inch (1.3 cm) and then, slice the onion in half. Freezing whole onions is not recommended (see the FAQs at the end for more information).
Chop the onions to the size you prefer—sliced or diced, but make sure that the pieces are no smaller than ½-inch (1.3 cm) because they might become encased in ice.
You can use a knife, mandolin, or food processor to cut the onions. We like to use the food processor when we’re doing large batches. We equip the device with a slicing blade for sliced pieces or a regular chopping blade for diced ones.
Bear in mind that if you’re using the food processor for diced onions, you should only pulse a few times to avoid turning the onion into tiny, mushy pieces. We recommend that you check the size of your onion pieces after pulsing the food processor twice, and then pulse one or two times more if necessary.
Lay out the onion pieces on a baking sheet lined with parchment paper. Spread them out in a single layer, making sure that they’re not overlapping. If the pieces are touching each other, they’re going to freeze together as one big clump that will be hard to separate and measure when you want to use them.
Don’t worry if you have a large number of onions, you can simply use multiple baking sheets, or freeze in batches if you don’t have enough room or in your freezer.
Flash-freeze the onion pieces for 1 to 2 hours, or until frozen solid. This step is quite useful if you want to prevent freezer burn and better preserve the quality and standard of your bulbs.
Divide the onion pieces into small portions. It’s better to use several smaller bags with just the portion you would typically use in your recipes, than a large one you have to thaw to separate the pieces. Bear in mind that onions don’t refreeze well.
We like to freeze them in 1 and 2 cup portions, or in a thin layer so that we can easily break frozen pieces off as needed.
Transfer the onion to a zip-lock bag or freezer-safe container. The quality of the container is very important when it comes to freezing onions, otherwise, you’ll end up with odor leaking out.
Freezer-grade bags work well, but you need to remove as much air as possible from them. Use a straw tucked in the corner of the bag to suck the air out, or submerge the bag up to the zip in water so that the air is pushed out.
Close the container, and use a permanent marker to label and date it. This way, you can know how long your bulbs have been in storage later on.
Place the container back in the freezer, and store your onions for up to 6 months!
How to Freeze Onions as Purée
Onion purée is commonly used for curries, stews, and sauces, but it can also be a great addition to a burger, pizza, steak, and even to a quesadilla. For this reason, it can come in handy to have some frozen onion purée in your freezer that you can use to add a touch of flavor to your dishes.
Use a sharp knife to trim off the top and bottom of your onions, and peel off the papery skin. Wash the bulbs under cool, running water to remove any dirt and debris. Then, cut them into smaller pieces that can fit in your blender.
Place the onion pieces in a blender, and using the purée setting, hold down on the button to ground the onions into a thick, but smooth, purée.
Remember that you should never overfill the blender’s pitcher, as it can prevent the appliance from working properly and even damage the motor. If you have a large number of onion pieces, just work in batches.
Use a spoon to transfer the purée to muffin tins or ice cube trays. Cover the tray with a sheet of plastic wrap to prevent the onion odor from leaking. Place the tray in the freezer, and flash-freeze it for about 4 hours, or until frozen solid.
Transfer the onion cubes to a freezer-safe container or thick plastic bag. Label and date the container, and place the onions back in the freezer. Store them in the freezer until you’re ready to use them, but make sure to do so within 6 months.
How to Freeze Green Onions
Green onions, also called scallions, can be preserved in the freezer just like regular onions. Just slice off the roots and leaf tips, wash under cool running water to remove any dirt and debris that might be sticking to it, and dry thoroughly.
Proceed as you would with regular onions, chop the green onions into pieces, flash-freeze separately, and transfer to freezer-safe containers.
Other options include storing your flash-frozen scallions in plastic bottles to create a convenient shaker dispenser, or freezing them in muffin tins or ice cube trays.
Some people prefer to freeze the leaves and bulbs separately as well, so think about how you’re going to use the frozen product before making your own decision.
Frozen onions are just as good as fresh ones, as long as you plan on cooking them. They can be used in soups, stews, pot pies, casseroles, chili, sautéed with ground beef, and more! You don’t even need to thaw them, simply toss them into your preparation, and they’ll defrost as they’re cooked.
Onions that have been frozen won’t brown as fresh ones would, since the ice crystals that form inside the cell walls within the bulb will prevent this from happening.
However, onions lose some of their crispness in the freezer, so we don’t recommend using them if you need raw onions for a salad or a sandwich, for example.
Frequently Asked Questions
Frozen onions can hold in the freezer between 3 and 6 months before they start to lose some of their quality.
Freezing whole onions is usually not recommended because they take a long time to thaw and are hard to use. Since there are really no recipes that call for whole onions, it’s best to cut them before freezing.
If you’re completely sure you want to freeze whole onions, you need to blanch them. Blanching involves boiling them for about 3 minutes if they’re small, or 7 minutes if they’re large, until their center is completely heated. Then you have to transfer them to an ice bath and let them sit for the same amount of time you’ve boiled them. It’s really not very convenient because you’ll still have to slice them after thawing.
Yes, you can! Simply follow the instructions on how to freeze fresh onions. Namely, prepare the red onions by washing them and chopping or slicing them, flash-freeze them into individual pieces, and transfer them to freezer-safe containers.
We’ve always recommended blanching when freezing vegetables such as carrots or zucchini to preserve their texture and flavor better. However, The National Center for Home Food Preservation states that diced or sliced onions don’t require blanching. They do recommend blanching whole onions, green onions, and onion rings.
Unblanched vegetables are subject to flavor changes over time when frozen. The longer they’re stored, the stronger their flavor becomes. The texture of frozen onions will change as well, as they become much softer and lose their crispness.
Knowing how to freeze onions can be quite useful when you’ve had a big harvest or found a great deal at the Farmer’s Market. There are many ways you can do it, but they’re all just as easy.
If you follow our tips and recommendations, it shouldn’t take you long to start freezing your onions like a pro! Hopefully, you’ll be enjoying the fruits of your labor for months to come.