Slow Cooker Caramelized Onions Recipe | Vegan in the Freezer (2024)

FAQs

Can you caramelize onions and freeze them? ›

Caramelized Onions Recipe Tips

Stored in an airtight container in the fridge, they'll keep for a week. You can also freeze them for up to two months. I like to freeze caramelized onions in ice cube trays. That way, I can easily thaw enough for a single dish and save the rest for another use.

In your largest heavy-bottomed pot over low heat, warm the oil. Dump in the onions and salt and stir to combine. Cover the pot until the onions begin softening, lifting the lid and stirring every 5 minutes, at least 30 minutes. Uncover and cook the onions, stirring every 20 to 30 minutes, for about 6 hours.

The thing about cooking so many onions, though, is that you probably won't need that many at one time. So there's an essential second move whenever you're making caramelized onions: Freeze them. Stashed in an ice cube tray, caramelized onions will keep indefinitely in the freezer.

You really want to give onions at least 8 hours to caramelize properly in a slow cooker. That low and slow cooking process is all about building flavor. If you can, let them go longer! Cook them for up to 12 hours for the richest flavor possible.

Refrigerate caramelized onions in a tightly covered container for up to 1 week. Freeze caramelized onions in a freezer safe zip top bag or a freezer safe container for up to 3 months.

Not only do onions freeze exceptionally well, it truly is as easy as chopping them up and chucking them in the freezer. There is no need to cook them first, unless, of course, you'd like to be able to quickly add the depth of flavor that caramelized onions provide to a dish.

You can use either oil or butter to caramelize onions — but ideally, you use a combination of both! I like to use olive oil, and this cooking fat tolerates heat particularly well. Meanwhile, butter adds a distinctly rich flavor to the caramelized onions.

Tip: use apple cider vinegar for white and yellow onions and balsamic vinegar for red onions. Tip: the vinegar serves to deglaze the pan, adds acidity, and brings this recipe together by boosting the tangy and savory flavors of the caramelized onions. If the onions stick to the pan, that's fine.

Our Test Kitchen likes to use butter when caramelizing onions, as it offers the richest flavor. If you avoid dairy or don't have butter, you can caramelize onions in other fat such as margarine or olive oil. Add the onion slices. It's okay if they overlap a bit here because they'll shrink as they cook down.

Let the cooked onions thaw in the refrigerator overnight before adding to soups, pastas and braises, or using as a burger topping.

Why are my caramelized onions soggy? ›

You may be cooking them on too high a heat, leading them to caramelize before all the liquid they release has evaporated. Try lowering the heat and giving them more time. Some onions are wetter than others, so you need to keep an eye on them and see how much liquid they release.

You definitely want the flavor of butter in your onions—but butter has the tendency to burn. For insurance, use a combination of butter and oil, which has a higher smoking point. But how much do you use? Depending on the consistency you want your onions, you can use more or less fat.

If you cook red onion with alkaline foods, such as nuts, lentils, and some vegetables, those anthocyanins revert to their blue hue. The same is true of red cabbage. To maintain the red hue, add a little acid, such as a splash of vinegar or a squeeze of lemon juice.

Slow cookers are designed to cook food over a long period of time at low temperatures, which makes them suitable for cooking frozen vegetables as well.

Just slice up a bunch of onions. (You can use white, yellow, or red onions, or a combination of any of those.) Toss them with some melted butter. Then let them cook on low for about 12 hours total until they reach that perfectly caramelized, deep golden brown, sweet and savory perfection.

Now, not everyone has 45 minutes to make caramelized onions for a weeknight dinner. I get it! The good news is that you can make a big batch of caramelized onions and keep them in the fridge to use throughout the week. You can also freeze caramelized onions and they're just as delicious when thawed and reheated.

For frozen vegetables like spinach and onion, Goldfield recommends sautéing them in a pan to reduce excess water before adding them to your meal.

Caramelized onions will keep for up to 5 days in an airtight container in the fridge. The fat will separate from the onions, but a quick reheat in the microwave or on low on the stove combined with a bit of stirring will revive the texture.