How to Caramelize Onions

How to caramelize onions the proper way takes longer than just 20 minutes. It’s not a quick thing. But it is an easy thing. All it takes to truly coax onions to a complex sweetness is a little more time that’s largely hands-off and offers the taste and texture that only properly caramelized alliums offers. Here’s how to do it right.

A skillet with caramelized onions and a spatula moving the onions.

We know, we know. You’re busy. You’re impatient. You’re rushing cuz you’ve got places to go, people to see, babies to kiss. And you’re thinking you can’t possibly afford to spend an hour of your life waiting for onions to caramelize. We think you can. Taste a spoonful of this and then tell us it ain’t worth it.–Renee Schettler Rossi

How To Caramelize Onions

  • Quick Glance
  • (1)
  • 25 M
  • 1 H, 25 M
  • Makes about 2 cups
5/5 - 1 reviews
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In a large skillet, heat the oil over medium heat. Add the onions and cook, tossing and stirring occasionally, for 15 to 20 minutes, or until softened. Reduce the heat to low and continue cooking, stirring occasionally, for another 50 to 60 minutes, or until the onions are completely soft and caramelized. They will look dark brown and mushy.

Remove the skillet from the heat and add the salt, pepper, and thyme, if using, and stir well. Go ahead and use your caramelized onions immediately or stash them in an airtight container in the fridge for up to 1 week. Originally published February 5, 2014.

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    How To Make Caramelized Onions In Advance

    • Why not caramelize a BIG batch of onions when you’re in the kitchen when it’s no big whoop to stay close to the stovetop and show the wilting alliums some love by stirring them on occasion. Maybe a random Tuesday night while you’re making dinner. Or a Sunday morning while you’re flipping flapjacks. Then cram the caramelized onions in a jar or other resealable container, stash them in the fridge for up to a few days, and you’ve got magic waiting to happen. Slather them on a sandwich. Strew them on savory tarts. Toss them with pasta and blue cheese. Or sneak them onto breakfast pizzas. You won’t be sorry.

    Recipe Testers' Reviews

    Here's a great use of +/- 60 minutes. Even if the end result wasn’t magnificent, there is the aroma of 60 minutes of deliciously fragrant onions all through the house. But the end result is magnificent.

    Because I was making these for a dish I felt would be plenty salty, I did not salt at the end, though I did pepper generously. If I'd have been smarter, I would have made a double batch, one for the recipe I was working on and one to stash in the fridge for later.

    As for timing, my onions were well softened after the full 20 minutes, and took 45 more minutes to become dark brown and mushy. I probably futzed with the onions more than necessary during the hour, but there is still plenty of time to keep these going while attending to something else, or to relax for an hour while allowing the onions to take their time browning and softening.

    They never even had a moment to cool before I used them in another recipe. If I didn’t have a plan for them, I would salt and also use the optional fresh thyme.

    Low and slow. That's the sorta flame you need when coaxing out the complex sweetness of caramelized onions. Not this 20 minutes business. (I once got into a heated argument with a colleague at a newspaper about what exactly constituted properly caramelized onions. Unsatisfied with our stalemate, I ran to my rolodex of chefs and he ran to his, and the duel was on. Needless to say, no chef in his or her right mind would agree that 20 minutes was sufficient.) This technique and timing does it right.


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    1. Renee,

      Love the use of the word “ain’t”—I like to sneak that into conversation/writing every now and again, too. I also love “Ouida’s ‘flavor bullets'”, great term. This is a great reminder for me to work on a better-stocked pantry/freezer.

      KirbyTails brings up a question I have: Is it “cheating” to add sugar to the onions while caramelizing? A chef friend and I say, yes, it is cheating…yet, having said that, I’ve been known to cheat (although not with brown sugar, which I’m going to try next time). I add sugar when I’m in a bit of a rush—usually around the 30-minute mark. What do the peeps at LC think about adding sugar?

      1. Rhonda35, I don’t think it’s cheating, if you believe the onions won’t sweeten to the degree you want. I haven’t done it much (only when I’m in a hurry), but we’re a no judgment zone here….

        1. Hi David – Oh, I know the crew at LC is cool! I guess I’m wondering if it makes a difference in some way or if there’s some reason a chef would not want to add sugar? Obviously, it could add “too much” sweetness to the onions…maybe it’s one of those things where chefs pride themselves on bringing out the sweet, caramelized flavor without any help – making it a bit of an art?? (I only add sugar when I’m trying to hurry things along, as well.)

          1. Hi, Rhonda. I think it’s simply a matter of classic technique. Caramelizing onions doesn’t call for sugar, so I think it’s drilled into them. And, of course, with the proper time and cooking, all onions because incredibly sweet.

      2. Hey Rhonda, so relieved to know that at least one LC reader is as laid back as I am in terms of language! Many thanks for taking the time to say so. As far as adding sugar, I agree that it is cheating, I guess the bigger question is do we consider this sorta cheating okay? I haven’t done it, though I don’t frown upon it, depending on the final use. After all, the ends justify the means, yes? But I speak only for myself. Curious to hear what others think. I’m also curious to give the sugar trick a twirl!

        1. For savory, somewhat salty caramelized onions, I like to add soy sauce after the onions are browned and are almost done. Soy sauce burns and gets very sticky if added to soon. I like to add the mushrooms as a tasty topper for burgers or London broil.

    2. I’m so glad you went into detail about this, Renee. I can’t tell you how many recipes I’ve found that call sautéed onions, caramelized onions. I love them both, but there is a difference!

      Speaking of additions, I love a few mission figs quartered and cooked in with the onions the last 10 minutes or so. I got the combination from a pork roast recipe from Elise Bauer of Simply Recipes. It’s been a struggle not to cook onions without the figs since! They are that good!

      1. So lovely to hear it, Susan. I completely agree, there’s a time and a place for all manner of cooked onions. Just please don’t mess with my caramelized ones. You’ve got me wobbly in the knees thinking of adding figs (and, dare I suggest, a splash of balsamic) to the onions during the late stages of caramelizing. Lovely. Many thanks for sharing…

    3. These are one of my secret ingredients (the other is roasted garlic), both of which I make in quantity and then freeze in small sizes (1/4 cup for the onions, 2 tablespoons for the roasted garlic). It’s so very easy to pop these flavor bullets into almost any savory dish–straight from the freezer. Oh–there’s another one, too: slow-roasted tomatoes. Ditto the above.

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