How to Caramelize Onions

Caramelized onions add the perfect bit of savory sweetness to so many of our favorite dishes. French onion soup would be nothing without a good base of these soft, sweet onions. They also add so much flavor to sandwiches, steaks, burgers and so much more. While caramelizing onions can take a bit of time, it’s an easy technique that you can master at home. All you need is a good pan and a little patience.

What Are Caramelized Onions (and How Are They Different from Sauteed Onions)? 

Before we get into how to make caramelized onions at home, let’s sort out what this delicious addition really is and how caramelized onions differ from other cooked onions.

Caramelized onions are simply onions that are cooked for an extended period of time with a bit of fat (either oil or butter). This extended cook time allows the natural sugar in the onions to brown and caramelize. This gives the onions a sweeter flavor and also a depth of flavor since as well all know color means flavor.

As for how these onions compare to sauteed onions the big difference is time. Sauteed onions don’t spend as much time on the heat. They get soft and they may brown a bit, but sauteed onions only take a few minutes and still retain their sharp, onion flavor. Caramelized onions are a labor of love and taste sweeter.

How to Make Caramelized Onions

Making caramelized onions is very simple. All you need is a heavy pan—a cast-iron skillet works especially well here—and two ingredients: onions and butter or the oil of your choice. You can use any type of onion here, but yellow onions tend to caramelize most easily and are the most versatile.

As for how many onions to use, that’s up to you. Onions are mostly water and lose about two-thirds of their mass during the caramelization process. If what you slice looks like a lot, don’t fret since they’ll reduce significantly.

Step 1: Slice the Onions

This should be standard operating procedure for most home cooks. Start by slicing off the top of the onion and then cutting the onion in half. Remove the skin. Then slice the onions into thin slices—about a quarter-inch wide. If you slice thinner, the onions are more likely to burn.

Step 2: Prep the Pan

Heat your pan and a few tablespoons of oil (or butter) over medium heat before adding the onions. A cast-iron skillet or even a Dutch oven works well for caramelizing onions. If you don’t have either, your heaviest skillet will work just fine.

If you’re wondering can you caramelize onions without oil? the short answer is no. You need the oil to help coat and brown the onions properly. If you skip the oil, you’ll likely just char and burn the onions which isn’t tasty.

Step 4: Stir and Wait

Add in the onions and stir them to coat them with the oil. Stir the onions occasionally—about once every five minutes. Be sure to stir from the bottom so you can loosen any onions sticking to the bottom of the pan.

When you see the onions starting to brown, reduce the heat. Continue stirring occasionally and keep cooking until the onions are sweet and brown—that’s usually 20-30 minutes. As you get to the end of the cooking time, keep a close eye on the onions and stir more frequently. The last few minutes are when they’re most likely to burn.

Step 5: Add More Flavor

When the onions are browned to your liking, you can remove them from the pan and serve. However, you can dress them up a bit if you like:

• Deglaze the pan: You can remove the onions easily from the pan (and add more flavor) by deglazing with the liquid of your choosing. You can deglaze the pan with broth, stock, wine, beer or even just a bit of water.
• A splash of vinegar: Adding a touch of balsamic vinegar to caramelized onions can add a great depth of flavor. A little goes a long way, so just add a touch at a time until you reach your desired taste.
• Herbs and seasoning: You can spice up your onions, too. Salt, pepper, fresh herbs—it’s all up to you. If you need help deciding, just add a sprinkling of the seasonings you’re using elsewhere in your meal.

How to Store Caramelized Onions

If you don’t manage to eat all of your caramelized onions, you can store them easily. They’ll keep in the fridge for up to four days. You can also freeze them for up to three months. Caramelized onions are so versatile that we’re sure you can find lots of excuses to use them during that time.

Next, try some of these onion recipes.