The *Right* Way to Caramelize Onions

Because there’s no such thing as caramelized onions in under an hour.

April 17, 2023
Photo by Food52

While following a weeknight pork ragú recipe from a celebrity chef who shall remain nameless, I came across the following, offending phrase in the method: “Cook onions until caramelized, 25 to 30 minutes.”

It doesn’t seem to matter how many articles, books, or cooking shows try to set the record straight. Even the experts among us cling to the hope that it’s possible to caramelize onions in 20 or 30 minutes, when in reality it takes about an hour to do it properly.

Perhaps we’re loath to commit so much time to an ingredient that always plays a supporting rather than starring role in recipes (unless you count this beloved braised onion pasta). Or maybe we’re playing a little fast and loose with the term “caramelize,” which at its simplest means the browning that occurs when foods containing sugar are introduced to heat. Searing sliced onions in neutral oil over high heat will indeed soften and make them deliciously brown in places in as little as 10 minutes.

But these are not Caramelized onions with a capital C: that intoxicating, mahogany jam that lends sweetness and rich, savory depth to everything it touches. Caramelized onions are “an onion transformed,” as chef and award-winning cookbook author Tamar Adler describes them—and they’re only achieved with time, attention, and patience.

Caramelization Versus Maillard browning

Onions contain an impressive amount of sugar: some 4.7 grams (1.2 teaspoons) per medium (roughly 110-gram) onion, according to the U.S. Department of Agriculture. As food scientist and author Harold McGee writes in On Food and Cooking: The Science and Lore of the Kitchen, onions store their energy in chains of fructose sugars. Cooking them slowly for a long time breaks down these structures, coaxing out their inherent sweetness. As moisture is released—fresh onions are nearly 90 percent water—and the onion’s natural sugars slowly heat up, they caramelize, while the onion simultaneously undergoes a chemical reaction known as Maillard browning. (An important distinction: Caramelization only requires the presence of sugar, while the Maillard reaction is a chemical reaction between amino acids and sugars.)

Join The Conversation

Top Comment:
“Y'all need to use an electric non-stick skillet, those big rectangular kind. It's way easier than stove/range top. Holds more onions in a shallow layer, and keeps heat steady (350F if you want to do it in 45-60 minutes). ”
— Karl

In my experience, it takes at least 45 minutes for the onions to start to really relent, melt, and deepen in color. But if someone asks, I usually round up to an hour—or better yet, as long as they can stand to be there, babysitting a slow-cooking heap of onions.

Adler sympathizes with the home cook’s hesitancy to devote so much time to such a mere component of a dish. “I found a kind of loophole in talking about how long it really takes to caramelize onions,” she says. “I wrote in my first book An Everlasting Meal: Cooking With Economy and Grace just about caramelizing onions—like, just doing that, rather than making it part of a larger dish. The way I approach it is, if you’re going to be a bear, be a grizzly bear—meaning if you’re going to take the time to caramelize onions, do enough so you have the ingredient around for a while.”

How to properly caramelize onions

This brings me to Adler’s caramelized onion recipe from An Everlasting Meal. It’s one of my favorites because it’s simple, yet just finicky enough to demand my regular attention throughout the process. Most importantly, it confidently asserts that “this will take 45 minutes to an hour.” Here’s the method:

  1. Cut off the tops of 8 to 10 onions, then cut them in half through their roots, then lengthwise into slices about a quarter-inch thick.
  2. Warm 3 tablespoons each of butter and olive oil in a big pot. When the butter is melted, add the mountain of onions, a small pinch of sugar, a big pinch of salt, and stir well.
  3. Cook the onions over medium-low heat, stirring occasionally. Add occasional sprinkles of water if the onions begin to stick, she continues. If they start to sizzle, lower the heat and cover the pot, then uncover it again when the cooking has slowed.

Adler tells me she prefers the biggest yellow onions she can find for this recipe to minimize peeling. She favors equal parts olive oil and butter—oil to keep the butter from burning, butter for its round flavor and the sheen it gives the onions. She doesn’t always add sugar, a variable she looks to more for boosting sweetness than encouraging caramelization. She likewise can’t give an exact measurement of water. “Adding a few drops at a time lets you understand the rate at which water evaporates,” she tells me. “It’s a little absorbing lesson.”

She hadn’t tried (much less heard of) the so-called baking soda hack, in which a few pinches purportedly speed up the caramelization process to a mind-boggling 13 minutes, according to the National Onion Association’s successful attempt. Adding baking soda makes the onions more alkaline, increasing the speed of the Maillard reaction so they brown more quickly. But it also imparts a chemical-like bitterness to the end result. Adler hasn’t tried caramelizing onions in the oven on moderate heat, either (another method I unearthed that seems to work reliably well, at the expense of up to several hours).

Instead, her straightforward technique calls us to the stove with the task of observing, learning, and reacting—stirring periodically, adjusting the heat, covering and uncovering the pan, and sprinkling in water droplets if the bottom of the pan starts to burn. We can almost hear her voice in our heads as we go, reassuring us that the whole mass will look “soggy and unconvincing” right up until the onions are ready.

When the onions do finally melt into that elusive golden jam, we can keep it on hand to transform fried rice, soup, scrambled eggs and even sliced toast with broiled Gruyère and a few magical spoonfuls. Adler’s favorite method of late involves adding caramelized onions and smashed raw garlic to yogurt, which she tosses with short pasta in a nod to manti, or lamb-filled dumplings in yogurt sauce.

Of course, we don’t have to worry about making any of that until tomorrow. Today is just for the onions.

Recipes for Your Caramelized Onions

What's your favorite way to use caramelized onions? Tell us in the comments!

See what other Food52 readers are saying.

  • AlexisCox33983
  • kitchensquatter
  • ElleT
  • wahini
  • Deborah
Chicago-based food critic & freelance writer


AlexisCox33983 April 29, 2023
Lovetocook -use these carmelized onions on pizza and flatbread. Sooo, good.
kitchensquatter April 29, 2023
Is there some way to get Food52 'Light' without all the intro verbiage? I just want the recipe, cut down to its most basic form, not the whole enchilada of the why's and how's and don't dos. I scroll through enough food and recipe tomes online that I prefer to have a minimal, cut to the chase version. Thank you!
ElleT April 28, 2023
Adding water worked for me: https://www.americastestkitchen.com/cooksillustrated/articles/517-quicker-caramelized-onions
wahini April 28, 2023
I rarely use my slow cooker but when I do it’s usually to caramelize a large quantity of onions. Onions, butter, a big pinch of salt, a bit of sugar—and 12 to 24 hours is all it takes.
CBA April 28, 2023
Wahini, no need for any liquid? Do they actually brown in the crock or is there a 2nd step after?
Deborah April 27, 2023
About time someone was honest about the time it takes to caramelize… really caramelize onions!!! Thank you!!!
CBA April 27, 2023
When I caramelize onions, it’s such a labor that I do a big batch & freeze it in snack size freezer ziplocks. This allows me not to thaw too much or too little when I need a little (to top a couple of burgers) or a lot (French onion soup). I use a mix of EVOO & butter + salt, pepper & some brown sugar & a mix of yellow, white, red, Vidalia & shallots
sws April 27, 2023
A true labor of love! I have had really good results using the Instant Pot for the onions. Pressure cook them down and then sautee until jammy-brown and delicious. May not be quite as yummy as the traditional method, but really close and I'm much more likely to actually cook up a batch!
Nancy H. April 20, 2023
Thank you for telling the truth about how long this process actually takes - I've sometimes wondered if I'm doing something wrong since it always takes me a lot longer than 25 minutes! I use less fat (2 tbsp. per kg. of sliced onions) and add the salt once the onions have just started to colour - no sugar since I find that the yellow onions are always sweet enough at the end. Have tried using butter only and love the almost "desserty" caramel flavour that results. However, I prefer the more savoury notes of EVOO: will try the mixture of both next time with pleasure :)) You really do need to be spend some dedicated time close to the stove, and be prepared to splash in a tbsp. or so of water when needed to keep the browning process more gradual. Like the poster below, I start with a covered pan and uncover it once the moisture has mostly evaporated. Dedicated attention brings great rewards!
Nancy April 17, 2023
Note: There is controversy where Manti originated. Whether it be Armenia, Mongol, China or possibly Turkey It is not necessarily of Turkish cuisine origin.
Smaug April 17, 2023
I've found that you can speed things up some by covering the skillet for the first part of the process, during which you're really only cooking moisture out of the onions. You'll get a lot of moisture buildup in the pan, but it will cook off quickly once you remove the lid.
I usually don't have trouble with the time spent- when I use caramelized onions, it's usually a day when I'm spending time in the kitchen on other things too, just have to remember to stir them regularly.
czinko April 27, 2023
Agree - I always start out with a lid on the onions. I also set a timer and keep an eye on the gas flame, starting at medium and then reducing the heat when I take the lid off. It's easy to forget you're cooking the onions, so set your timer for 5-minute increments. That way you don't have to remember and you will prevent yourself from burning them accidentally.
AntoniaJames April 17, 2023
I tend to agree to Kenji, who points out that there may be instances where the quicker caramelization methods are quite appropriate. See, e.g., https://www.seriouseats.com/channa-masala-recipe . When I made that channa masala a few weeks ago, I found the depth of flavor produced by his method to be quite satisfactory. I would not use this process in all instances, but for that, it turned out well. ;o)
Karl April 17, 2023
Y'all need to use an electric non-stick skillet, those big rectangular kind. It's way easier than stove/range top. Holds more onions in a shallow layer, and keeps heat steady (350F if you want to do it in 45-60 minutes).