What You Need To Know Before Caramelizing Onions In A Slow Cooker

Caramelized onions are a versatile and delicious ingredient to keep on hand. They upgrade even the most basic burgers or mashed potatoes with their sweet and savory flavor profile. Although there are many alleged short-cut recipes online, slow cooking over low heat for many hours is the only way to achieve deep caramelization. Linda Miller Nicholson of Salty Seattle's rainbow pasta fame even calls these recipes a "pet peeve" on Instagram, insisting that it takes at least eight hours to caramelize onions.

With all that in mind, it would stand to reason that caramelizing onions in a slow cooker would seem like a genius hack. After all, you can put them on and let them cook overnight, worry-free. But there is one thing to keep in mind when using a slow cooker to caramelize onions. It requires extra steps to control how much moisture you want to cook out of the onions. If too much moisture is left over, you might have a soggy goop of stewed onions instead. If you want denser, jammier caramelized onions, there are a couple of ways to reduce that liquid down to the right consistency.

To make sure your slow-cooked caramelized onions reach your desired consistency, first, cook the onion slices for eight to ten hours on the lowest setting. At this point, they may be just what you're looking for. If not, then, simply remove the lid to allow the moisture to escape, and continue cooking for a few more hours on the same temp setting. Peek at your caramelizing onions every hour or so, and take them off when they've reached the color, flavor, and consistency you're looking for.

If using a multicooker, cook the onions on low for the same length of time, then change to the sauté setting. The water will cook off relatively quickly, reducing the need for you to spend those few extra hours. Want to cook the water off even faster? Transfer the cooked onions to a skillet after the slow cooking stage, and carry out the sautéing part on the stovetop. For both these sauté methods, you will need to pay a little bit more attention to your onions, but for a shorter amount of time.

There are other tried-and-tested methods to ensure successfully caramelized onions, and many of them apply to cooking them in a slow cooker. To start, make sure they're sliced length-wise evenly, and not too small, about ¼ to ⅛ inch. One of the most important tips is to use onions that are not already very sweet. Since caramelizing them brings out a considerable amount of natural sugar, opt for a kind that's less sweet, like yellow or Spanish.

Remember to add butter and oil to the onions, both to flavor and lubricate them during cooking. Salting at the start helps the flavors penetrate deep into the onions, and a dash of brown sugar accelerates the browning of the natural sugars in the onions. Once the liquid has been cooked off and the texture, color, and flavor of the onions are to your liking, you can proceed to use this tasty ingredient in a variety of dishes. If making a big batch, let the caramelized onions cool before storing them in the fridge for three to five days, or the freezer for up to two months. Just avoid these common mistakes when preparing caramelized onions, and you're good to go.