Tips & Techniques

The Truth About Caramelizing Onions

April 17, 2017

"It might be the most valuable journalistic work I’ve ever done."

That's reporter Tom Scocca, who has covered presidential elections and the Supreme Court nominations, reflecting on a piece he wrote five years ago for Slate in which he snuffed out recipe writers' biggest, baddest fib: the time it takes to caramelize onions.

Just imagine the soup! Photo by James Ransom

The article, which indicted everyone from Melissa Clark (10 minutes to become "soft and caramelized," she says!) to Madhur Jaffrey (5 minutes for a "medium-brown colour"!), resurfaced last month, when Scocca realized that the featured Google search result for "How long does it take to caramelize onions?" drew—and, to add salt to the wound, directly from his article—on the very information his entire piece had set out to expose as false: "about 5 minutes."

As long as I've been cooking, I've been reading various versions of this lie, over and over.
Tom Scocca

(Since this revelation, the Google search results have been adjusted, now pulling a more relevant quote from his original Slate article.)

Join The Conversation

Top Comment:
“A friend gave me an absolutely wonderful recipe/method for carmelizing onions: Roasted in oven for 2hours, on covered baking sheet. 8 cups thinly sliced (abt. 3 XL onions), Mixed with 1/4 c. Dk. Brown Sugar, 1/4 cup maple syrup, 1/4 Balsamic Vinegar, 1 tsp. Kosher salt, 2 Tbl. Olive oil. Oven at 325. Drain onions before adding other ingreds. Spread onions onto large shallow baking pan, Cover with foil. Bake 2 hours. This method is absolutely perfect and doesn't need constant tending. Great for onion soup, quiche, on beef tenderloin. This is the first time I've shared with Food 52. You're so great and I've gotten all your books! A true inspiration for me. Thanks!”
— Karen F.

On Food52, we, too, have a lot of mixed information about onion caramelization in our archives. Some recipes say it takes 45 minutes to 1 hour to caramelize diced onions, while others recommend 30 to 40 minutes for thin slices.

The inconsistency isn't surprising: Our recipes are developed in the kitchens of home cooks who are using pans, different stoves, and different types of onions—and who are judging with their eyes and ears rather than by the time on the clock.

But to see how long caramelizing onions really take—and what they look like along the way—we caramelized three pans of onions (three onions, 1 tablespoon of butter, a stainless steel pan) for 15, 30, and 60 minutes over medium-high heat. Whenever the fond (those caramelized sugars that stick to the bottom) started to build up, we deglazed with a tablespoon of water, scraped up all of the flavorful bits, and started the whole process again.

Which of these look "caramelized" to you? Photo by James Ransom

You'll see in the photo that the onion volume reduced dramatically (after 60 minutes, three onions had turned into about 1/2 cup of deeply caramelized onion shmoo); the color changed from yellowish orange to a deep auburn; and what was once-astringent and watery turned candy-sweet and butter-soft. With this method, there was no defying time (and no outsmarting patience). But then again, some cooks might consider the 30-minute pan to be caramelized to perfection (as opposed to obliteration)—and for some applications, a half-hour might be plenty of time, indeed.

Next, we tried two tricks that are supposed to speed up the process: (1) adding baking soda (read more about the science behind that here), and (2) starting with the pan covered. (Both techniques also call for a bit of added sugar in order to speed up the caramelization process.)

In the end, neither method was significantly faster than the nothing-added 60-minute technique. But the onions they yielded differed in sweetness and softness in a way that might actually be preferable to you depending on how you're putting the alliums to use.

Would you consider all of these to be well caramelized? Photo by James Ransom

The shortcuts:

  1. Baking soda + sugar: In J. Kenji López-Alt's 15-Minute Caramelized Onions, you add 1 teaspoon sugar and 1/4 teaspoon baking soda to 5 cups of finely sliced onions at the start of the cooking process. You cook over high heat, using the same fond-scraping technique "until onions are completely softened and a deep, dark brown, about 15 minutes total." It took us 40 minutes (not 15) to achieve the pan of onions in the photo above.
  2. Starting with the pan covered: In this technique, which we learned about from Deb Perelman, you cook the onions, covered, over very low heat for 15 minutes, then turn the heat up to medium-high, add 1/2 teaspoon of sugar, and cook, stirring frequently, for 15 to 20 minutes, until they’re a deep golden brown. It actually took us closer to 65 minutes (rather than 35) to get the onions in the pan above.

The results:

  • The onions we cooked for 60 minutes were incomparably jammy and candy sweet—much sweeter than the onions in the other two pans even though this was the only technique that did not call for any added sugar. These are they type of onions that will melt into mashed potatoes or squash and sink into a flatbread. They were also the most depleted in volume, so be warned: If you're looking for a lot of these super-sweet, smooshy onions, you're gong to be doing a whole lot of slicing.
  • While not as soft or deeply flavored as the 60-minute pan, the onions that were given a baking soda boost were softer, sweeter, and more evenly cooked than the pan of onions that started covered. The onions don't lose as much volume in this method as compared to the 60-minute pan—so if you're short on raw onions but still looking for a soft, melting texture, consider this route.
  • The onions that started in a covered pan were a bit more scorched-tasting (perhaps because of the sudden transition from low to high heat) and slightly tangier than the other two pans. They held their shape the best of the group, making them good candidates for any place where you'd like your onions to keep their integrity rather than dissolve, like in a pasta or a curry.

So it doesn't take 5 or 10 minutes to caramelize onions. So the shortcuts might not be as speedy as they claim to be. But you can still get a pan of sweet, soft onions in 30 to 40 minutes.

But are they "caramelized"? Perhaps the problem lies not with our inconsistency about cook time but with our lack of specificity in regards to just how those onions should look, taste, and behave. What does caramelized mean? (I know—big sigh!) Are you looking for falling-apart, jammy onions? You'll need an hour. Or are you looking for onions that are just starting to turn from yellow to brown? You might only need 20 minutes.

If we can be more specific about our language—moving beyond "golden-brown" and "caramelized"—we'll be able to be more specific about cook times, too.

How many minutes do you typically spend caramelizing onions? Tell us in the comments below!



Maximus February 7, 2019
Gordon said it takes 4 hour...
Jack B. October 7, 2018
Here is a sure-fire way of caramelizing onions in 15 minutes or less:

1) Cut up a large yellow onion into large dice.
2) To a stainless steel 3 quart pot, add chicken fat to about a 1 inch depth, or until it will just cover the diced onions.
3) Turn on the heat to low so that the chicken fat melts.
4) Add the onions and stir with a flat wooden spatula.
5) Turn up the heat to maximum high and do not cover.
6) Set timer for 15 minutes and let sizzle, stirring occasionally.
7) After 12 minutes, edges of the dice should be starting to turn brown.
8) Stir and watch closely and when center of dice starts turning brown, turn off heat.
9) Let cool 5 to 10 minutes. and use the spatula to scoop dices into a container. You may want to add chicken broth to just cover the onions so that they absorb it to plump up.
10) Reserve fat for future use.
Karen F. October 7, 2018
Sounds good.
Fred R. September 3, 2018
While not a pressure cooker, years ago we had a slow cooker in which I made some caramelized onions a few times. They weren't even close in taste and texture to an hour and a half in an old iron skillet. Kind of a ball of mush. Maybe things are better today.
Joel September 3, 2018
I used whole onions (outer layer peeled) in a pressure cooker for about 10 minutes (4 to 5 'actual' minutes from the time the steam started to come out), then chopped them (you won't get normal looking rings, as they are super limp and hard to chop) and put them on the stove w/olive oil and got decent results in about 45 minutes- I probably need to experiment with longer/shorter pressure cooker times and longer/shorter skillet times, but it seemed to cut a little time.
dvb April 19, 2018
If you want Caramelized Onions without all the effort, time, and pain check out - great product!
GioFam March 7, 2018
For the record, I'm currently making you Diane Kochilas' Pasta with Yogurt and Caramelized Onions - and it still says "20-30 minutes" - LIES! (an hour in, and not there yet)
Francis M. June 29, 2017
Robby G. June 24, 2017
allis June 19, 2017
I use salt, lots of olive oil, and high heat until they start cooking fast. It takes close to an hour to get that jammy consistency
Philip T. June 7, 2017
One of the most important elements in caramelizing onions is moderating temperature over those long cook times. It's easy to get distracted and that beautiful pan of caramelizing onions is suddenly half burnt and bitter! It's been pretty amazing to watch the Hestan Cue ( cook onions evenly from start to finish with precise temperature more burnt onions!
Louise June 5, 2017
I cook mine in a covered Dutch oven in a 400 degree oven for 2 - 2 1/2 hours stirring every 15 minutes. They turn out fabulous and are worth every minute.

StevenHB June 4, 2017
I probably do 45 to 60 minutes, usually looking for onions that retain some shape as a topping for a focaccia (where they get cooked more when the bread bakes).
Carmen K. June 4, 2017
I typically do at LEAST 30 min. But may have to start trying the hour long carmalization process make a bunch and keep them in a jar in the fridge. I think it'll be worth it in the long run!!
Steve H. June 4, 2017
Depends on use but to push carmelizing forward, I use a dash of balsamic vinegar per onion. I only use salt in the middle of cooking if I want an onion jam.
judy June 3, 2017
I have a hand cranked food processor. I recently discovered that I can chop those onions into small bits even chop and then proceed to caramelize. The process now only takes about 25 minutes because a larger amount of surface is exposed to the pan, I would surmise. I don't like the baking soda method because the onions seem a little bit mushier. Walla Walla sweets and Vidalias' seem to be the best varieties. I do this for making the base of a large batch of Indian curry sauce to freeze. Works well.
jmmx June 3, 2017
I do this a lot to make meat stews or vindaloo-ish dishes (I do not claim for it to be a real vindaloo)

It takes me about an hour. I start with 4 - 6 really large onions on very high heat, and gradually reduce the heat as they first wilt then begin to caramelize.

My theory is that they need to cook off the water before they can begin to caramelize. As we all know, water will not reach a temperature over 212F or 100C (all the usual disclaimers).

I never add salt until later. My theory: salt draws out the water which keeps the onions under 100C. So if you add salt you are boiling the onions at first.

Like I said - these are theories (Based on a Science degree but not food science). They do come out tasty! But takes a long time

Thanks for a great article!
John D. June 8, 2017
You are right in both your theories. If you add salt initially you "sweat" the onion or macerate it to give up its water. Then you can carmalize. Sugars carmelized @ 320 to 360 degrees F. Water can not be heated over 212F or it evaporates.
jmmx June 8, 2017
Thanks John

BTW - cool story here (in 4 languages):
Bob K. June 2, 2017
Kenji is a political pundit.. What does he know about cooking?
S.Hartman June 4, 2017
You can have an opinion about politics AND know about science and cooking -- it's not really an either/or thing.
Corey O. June 2, 2017
I caramelize onions in just a few minutes using a pressure cooker. Brilliantly fast French onion soup...
Alison S. June 1, 2017
I thinly slice vidalia onions, add olive oil and butter and salt and pepper, then cook for about an hour, starting off pretty high temp stirring constantly then lower the heat and stir occasionally. The onions reduce in volume but are an absolutely delicious dark brown (not burnt) result. Perfect on burgers or anything else that appeals to you!
Andy June 1, 2017
I don't know about the methods for speeding up the carmelization process. But i know that adding carmelized onions to almost any dish speeds up the eating process! Yum!