Caramelized onions are a versatile kitchen staple that can elevate the flavor of many dishes. Whether you’re preparing soups, sandwiches, burgers, or pizzas, having caramelized onions on hand is always a good idea. But caramelizing onions from scratch can be time-consuming, and we don’t always have the luxury of standing over the stove for an extended period, stirring until they reach that perfect, sweet, and savory golden brown.

The solution? Freeze them! Freezing caramelized onions allows you to batch-cook and store them for future meals, saving time without sacrificing flavor. In this comprehensive guide, we’ll walk you through everything you need to know to freeze caramelized onions successfully.

Why Freeze Caramelized Onions?

Freezing caramelized onions is incredibly convenient. Imagine having these luscious, savory-sweet onions readily available whenever you need them. No need to worry about slicing and caramelizing onions from scratch when you’re in a hurry or simply don’t feel like spending an hour on prep.

• Save time: Batch-cook a large quantity and freeze in portions. Whenever you need a flavor boost, simply thaw and use them in your recipes.
• Reduce waste: If you have extra onions that are close to going bad, caramelizing and freezing them prevents waste and makes them last longer.
• Consistency: Caramelized onions can enhance a variety of dishes, and having them pre-made ensures you get consistent flavor in every bite.

Preparing the Onions

I have a more in-depth post about how to make the perfect caramelized onions if you’ve got some time but I’m also sharing a condensed version here.

Before you start the freezing process, you’ll need to properly caramelize the onions. Here’s a step-by-step guide:

Ingredients:

• 4-6 large onions (yellow, white, or red, depending on your flavor preference)
• 1-2 tablespoons of butter or olive oil (you can use a combination of both for extra richness)
• A pinch of salt
• Optional: A pinch of sugar to enhance sweetness or balsamic vinegar for extra depth of flavor

Cooking Method:

Step 1: Peel and Slice the Onions
Peel the onions and slice them thinly into half-moons. Try to keep the slices uniform, as this helps them cook evenly. A sharp knife or a mandolin slicer will make the job easier and quicker.

Step 2: Heat the Pan
Use a large skillet or a wide-bottomed sauté pan. The wider the pan, the more surface area for the onions to caramelize. Add butter, oil, or a combination of both to the pan and heat over medium-low heat.

Step 3: Add the Onions
Once the oil is hot, add the sliced onions to the pan. Stir them to coat them in the butter or oil. Cook on medium-low heat, stirring occasionally, and be patient. Caramelizing onions takes time—don’t rush the process with high heat, or you’ll end up burning them rather than caramelizing them.

Step 4: Stir and Cook Slowly
The key to properly caramelized onions is patience. You want to slowly draw out the sugars in the onions and let them cook down into a rich, golden brown color. Stir the onions every few minutes to prevent them from sticking to the pan or burning. If they start to dry out or stick, you can add a splash of water to deglaze the pan.

Step 5: Caramelize to Perfection
Depending on the quantity of onions and the size of your pan, the process should take about 30-45 minutes. The onions are done when they’re deeply golden and have a soft, jam-like consistency. If you prefer extra sweetness, you can add a pinch of sugar or balsamic vinegar towards the end of the cooking process.

Step 6: Cool the Onions
Once your onions are perfectly caramelized, remove them from the heat and let them cool to room temperature. You don’t want to freeze hot or even warm onions, as this can cause condensation and lead to freezer burn.

Freezing Caramelized Onions: Step-by-Step

Now that your onions are beautifully caramelized and cooled, it’s time to freeze them. Here’s the method to ensure they stay flavorful and fresh in the freezer:

Step 1: Portion the Onions
Decide how you’d like to portion the onions before freezing. This depends on how you typically use them. If you often add a small amount to soups or sandwiches, you can freeze them in small portions (about 1-2 tablespoons). For larger meals like casseroles, you might prefer larger portions (¼ or ½ cup).

There are several methods you can use to portion and freeze the onions:

• Ice cube tray method: Portion the onions into ice cube trays, pressing them down to pack them tightly. This is great for small portions, perfect for throwing into soups, sauces, or pasta dishes.
• Muffin tin method: For larger portions, use a muffin tin. Scoop the onions into each muffin cup and freeze.
• Baggie method: You can also portion the onions into small zip-top bags, flattening them out so they freeze evenly. This is a space-saving method and allows you to break off chunks of onions as needed.

Step 2: Flash-Freezing
Once the onions are portioned in ice cube trays or muffin tins, place them in the freezer for a few hours, or until they’re completely frozen solid. This ensures the onions freeze individually rather than clumping together, making it easier to grab what you need later.

Step 3: Transfer to Storage Containers
Once frozen, remove the onion cubes from the trays or tins and transfer them to airtight containers or freezer-safe bags. Label the bags with the date so you know when they were made. Caramelized onions can last up to 3 months in the freezer without losing flavor, though they’re best used within 1-2 months for peak freshness.

If you used the baggie method, simply label the bags and store them as is.

I like to use Ziploc Gallon Food Storage Freezer Bags because they don’t tend to rip and I can portion them in smaller sizes since you probably don’t use a ton of caramelized onions at once.

If you prefer to store larger portions, use airtight containers like the Freshware Food Storage Containers that are suitable for storing soup since then you have a larger batch and the juices will also be stored well.

Thawing and Using Frozen Caramelized Onions

When you’re ready to use your frozen caramelized onions, thawing them is simple:

• In the fridge: Transfer the portion of onions you need from the freezer to the refrigerator a few hours before cooking, or let them thaw overnight.
• On the stovetop: You can also thaw the onions quickly by adding them directly to a warm pan. They will soften and heat through in a few minutes.
• Microwave: If you’re in a hurry, you can microwave the onions for 15-30 seconds on low heat until they’re thawed.

Once thawed, the onions are ready to be used in your favorite dishes! Add them to grilled sandwiches, burgers, pizzas, stir them into pasta sauces, mix them with grains, or serve them alongside roasted vegetables or meats. The possibilities are endless, and the convenience of having them pre-cooked will make cooking much quicker and more enjoyable.

Tips for Success

• Cook low and slow: Properly caramelizing onions takes time. Rushing the process with high heat will result in burned onions rather than caramelized ones.
• Oil and butter: A mix of oil and butter helps with the caramelization process. Butter adds richness, while oil prevents the onions from burning.
• Keep them flat: When freezing in bags, flatten them out as much as possible. Not only does this save space in the freezer, but it also speeds up thawing time.
• Portion control: Think about how you’ll use your onions ahead of time. If you mostly cook for one or two people, small portions might be more practical.

Conclusion

Freezing caramelized onions is a game-changer for home cooks. Not only does it save time, but it also ensures that you always have a delicious, flavorful ingredient on hand for a variety of meals.

By following this guide, you’ll be able to caramelize onions in large batches, freeze them properly, and enjoy the convenience of having them at your fingertips whenever you need them. Whether it’s a last-minute dinner or a carefully planned gourmet meal, caramelized onions will be your go-to ingredient that elevates the flavor of almost anything they touch.

So go ahead, caramelize a big batch of onions and freeze them! Your future self will thank you.