How to Caramelize Onions

Caramelizing onions, by slowly cooking them in a little olive oil until they are richly browned, is a wonderful way to pull flavor out of the simplest of ingredients. Onions are naturally sweet; and as caramel comes from the simple cooking of sugar, when you slowly cook onions over an extended period of time, the natural sugars in the onions caramelize, making the result intensely and wonderfully flavorful.

You can use onions prepared this way on top of steak, or for onion soup, tarts, pizza, or onion dip. Or you can do what I did with this batch, eat it straight up. What are your favorite dishes to make that use caramelized onions? Please let us know in the comments.

By the way, I put together a time-lapse video of the caramelization process, which you can see at the end of this post. Enjoy!

From the recipe archive, first posted 2009.

How to Caramelize Onions

How to Caramelize Onions

  • Prep time: 10 minutes
  • Cook time: 45 minutes

Quantities depend on how much caramelized onions you wish to make. In this example, 5 large raw onions yielded about 2 cups caramelized onions.

Yum

Ingredients

  • Several medium or large onions, yellow, white, or red
  • Olive oil
  • Butter (optional)
  • Salt
  • Sugar (optional)
  • Balsamic vinegar (optional)

Method

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1 Slice 1/2-inch off the stem ends of the onions and the roots off of the root end. Place the onions cut side down on the cutting board. Cut them in half through the root end. Peel back the peels from the onions. Lay the onions cut side down and make angled cuts into each onion, aimed at the center, cutting almost all the way, but not completely through the root end.  Make the cuts to your desired level of thickness. The root end will help hold the onion together as you cut it, making it easier to cut. Then cut a V in the root end to cut out the tough root holding the slices together.

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2 Use a wide, thick-bottomed sauté pan for maximum pan contact with the onions. Coat the bottom of the pan with olive oil, or a mixture of olive oil and butter (about 1 teaspoon per onion). Heat the pan on medium high heat until the oil is shimmering. Add the onion slices and stir to coat the onions with the oil. Spread the onions out evenly over the pan and let cook, stirring occasionally. Depending on how strong your stovetop burner is you may need to reduce the heat to medium or medium low to prevent the onions from burning or drying out. After 10 minutes, sprinkle some salt over the onions, and if you want, you can add some sugar to help with the caramelization process. (I add only about a teaspoon of sugar for 5 onions, you can add more.) One trick, by the way, to keeping the onions from drying out as they cook is to add a little water to the pan.

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3 Let cook for 30 minutes to an hour more, stirring every few minutes. As soon as the onions start sticking to the pan, let them stick a little and brown, but then stir them before they burn. The trick is to let them alone enough to brown (if you stir them too often, they won't brown), but not so long so that they burn. After the first 20 to 30 minutes you may want to lower the stove temperature a little, and add a little more oil, if you find the onions are verging on burning. A metal spatula will help you scrape up the browned bits from the bottom of the pan as the caramelization proceeds. As the onions cook down, you may find you need to scrape the pan every minute, instead of every few minutes. Continue to cook and scrape, cook and scrape, until the onions are a rich, browned color. At the end of the cooking process you might want to add a little balsamic vinegar or wine to help deglaze the pan and bring some additional flavor to the onions.

Store refrigerated for several days in an air-tight container.

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Here is a time-lapse video I made of the caramelization process, to show how the onions cook down and caramelize over the course of an hour (https://vimeo.com/2917598):

How to Caramelize Onions

Showing 4 of 177 Comments

  • Elizabeth

    I can honestly eat them straight as well, but my favorite use is piled high on a medium-rare steak. Yum!

  • Bill

    Hi,

    I recently had to caramelize up some onions and tried this trick using a pinch of baking soda to speed things along.

    It worked *great* and you only need a tiny pinch for a couple of onions worth of cooking. Try it sometime :)

    Hi Bill, I tried the baking soda trick last week and found that it foamed up the onions a bit and made them a little mushy. I honestly didn’t see any increase in cooking time and was disappointed as I had heard that it would speed up the process. However, I didn’t add the baking soda until 10 min into the process, so maybe that had something to do with it. The taste was great though. Glad it worked for you. I may try again with fewer onions, or a little more baking soda, and the baking soda put in at the beginning. ~Elise

  • Adam Hickman

    I appreciate how you cut the onion. It’s nice to see that other people recognize the classic way to cut onions for caramelization, french onion soup, etc… Thanks for the blog, I make it a part of my routine every day.

  • Suzee

    I love caramelized onion with chopped canadian bacon and american cheese in an omlette! They are also great on pizza with extra sauce, grilled chicken and cheese, or added to lightly sauteed spinach – yummmmm :) I think I like them best next to a pan seared filet finished in the oven with a nice demi glace made from the cabernet I serve with dinner. Now if only I could get caramelized onions to like me as much as I like them :)

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