How to Caramelize Onions to Highlight The Veggie's Natural Sweetness

Two ingredients and a skillet are all you need for caramelized onions. Sautéing onion slices slowly in butter until tender brings out their natural sugar, creating an irresistible combination of savory and sweet.

Caramelized onions add the perfect amount of both savory and sweet flavor to many dishes (hello burgers, French onion soup, and dips). Wonder what caramelizing is? Well, all vegetables and fruits contain natural sugars. When heated, these sugars brown and caramelize, becoming more intense in flavor. Onions are great candidates for caramelizing because they contain plenty of natural sugars. Onions can be caramelized by cooking them slowly in oil. Or they can be caramelized using a little sugar. Read on to learn how to caramelize onions like a pro using our Test Kitchen's step-by-step process. From there, we'll include tasty uses for caramelized onions.

sauteeing onions in metal pan
You can caramelize onions by cooking them slowly in oil. Peter Krumhardt

How to Caramelize Onions

The best onions to use for caramelizing are sweet onions, since they tend to be juicy with a mild, sweet taste. Some popular sweet varieties include Maui, Vidalia, and Walla Walla onions. Once you've got you're onions, follow these steps to learn the best way to caramelize onions.

Step 1: Prep Onions

For 4 to 6 servings (about ⅓-cup each), start with two large onions and peel away and discard the outer papery layers. Use a sharp knife ($60, Bed Bath & Beyond) to cut the onions into thin slices or ¾-inch chunks.

placing raw onions into cooking pan
Blaine Moats

Step 2: Melt the Butter and Add Onions

Melt 2 tablespoons of butter in a large skillet ($25, Walmart) over medium-low heat. 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. If the skillet gets too full or you're making a lot of caramelized onions, consider using two skillets for more even cooking.

Step 3: Slowly Sauté Onions

Cook, covered, over medium-low heat for 13 to 15 minutes or until onion slices are tender, stirring occasionally. Low and slow is the key here. The slow cooking step allows the onions to release their juices and become uniformly soft.

caramelized onions on stovetop
Blaine Moats

Step 4: Finish Caramelizing the Onions

Once the onions are tender, turn up the heat to medium-high and uncover the skillet. The extra heat will help to caramelize the onion juices in the butter, giving the onions the desired caramel color and flavor. Cook, stirring constantly, for 3 to 5 minutes or until golden.

Caramelized Onion Dip
Andy Lyons

Uses for Caramelized Onions

There are so many delicious options for enjoying caramelized onions—although you may be tempted to eat them right out of the skillet. Spoon the caramelized onions atop juicy burgers, steaks, pork chops, or cooked veggies. For appetizers, top a warmed wheel of Brie cheese or bruschetta slices with caramelized onions. They'll also be a game-changing addition to family-favorite sides such as mashed potatoes or macaroni and cheese.

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