We Tried 6 Methods of Caramelizing Onions and Found a Clear Winner
Even though I’ve been cooking personally and professionally for more than a decade, perfectly caramelized onions have always been elusive. This is probably because I’m extremely impatient, and as Slate once famously pointed out, many recipes lie about just how long it really takes to achieve true caramelization (doing it in five minutes is not a thing).
Despite that, there is no end to the methods that claim to make the task faster or easier. I was determined to try as many methods as I could find. After some careful research, I found six that looked interesting: a basic stovetop method from Bon Appétit, a quicker (15-minute) method from J. Kenji Lopez-Alt, a slow cooker method from the Pioneer Woman, an oven-roasted method from Food Network, an Instant Pot method from Martha Stewart, and finally a stovetop method from Cooks Illustrated that suggested using a little baking soda.
There was really no downside to my mania, since caramelized onions make your house smell wonderful, have endless uses, and even freeze well so they’re great to make in bulk. And it was definitely worth the onion tears, given that I learned a few new tricks. Some of the methods are definitely better than others. And there was one that took a little more effort, but yielded far superior onions. I’m calling it the clear winner. But, spoiler alert, I don’t think any of the methods will honestly save you much time — not if you want that restaurant-level golden-brown perfection. Here’s a breakdown of each method, how I tested it, and my results.
Method: Basic Stovetop
Cook time: 45 minutes
About this method: As part of Bon Appétit’s “Basically” series, this is the most traditional method I tried, and it yielded predictable results. It never claimed to speed things up, but did distinguish between “soup” and “burger topping” doneness, which I appreciated. There are levels of caramelization, which correlate to differing depths of flavor, and not every dish wants (or needs) with the same level of doneness.
Because the method is simple (combine butter, onions, salt, and stir) the results were also pretty predictable. I probably didn’t stir as steadily as I needed, so I got less even browning, but the overall taste was still great. It takes a while, but it’s hard to screw up as long as you keep your attention on the pan.
Method: Quicker Stovetop
Cook time: 22 1/2 minutes
About this Method: Over at Serious Eats, J. Kenji Lopez-Alt put together a “quicker” method that, he claimed, made caramelized onions in 15 minutes, or about a third of the time. The trick, according to Kenji, is that you use a higher heat, but regularly deglaze with water, so the onions don’t burn.
Kenji has never steered me wrong in the kitchen, so I had high hopes for his method, and they were mostly justified. It was also the only technique I tried that called for very thinly sliced onions, which is how I like them — I prefer them well-done and almost crispy. There’s definitely something to be said for how simple this method is, too. All you need is a tablespoon of butter and some water for deglazing.
The only thing that detracted from this method was that I was sweating more than the onions. You have to keep both the heat and your attention on high the entire time, and all the water you add creates steam, which is hard to escape as you stand over the stove.
Aside from the heat and attention, the method is fairly easy, and the thinness of the slice plus high heat did speed things up. I wasn’t able to get it down to 15 minutes, however. It took 22 minutes and 30 seconds for mine to be done to my liking. So it was definitely faster, but nowhere near what Kenji claimed (at least for me). The resulting onions had a good, deep color and not-too-sweet flavor — perfect for topping a burger.
Method: Slow Cooker
Cook time: 12 to 14 hours
About this method: I’ve heard about the slow cooker method for a while. The main advantage that proponents tout is that it’s very hands-off. I’ll admit that I was pretty skeptical (using a plug-in device seemed un-foodie-like). But slow cookers are specifically designed for cooking things moist and slow, so in theory, I figured, it should work.
I shouldn’t have been skeptical. The slow cooker method works fine. And while the cook time requires planning ahead, it’s nice to be able to walk away, make other stuff, sleep, binge watch Black Mirror, and go about your day without worrying anything will burn. This is a boon for me, since my impatience and inattention always gets the better of me. My onions tend to end up crispy whether I want them to or not. In fact, while Pioneer Woman recommends 12 to 14 hours, I actually left them in the slow cooker for 16 hours. It didn’t affect the final product in the slightest.
Taste-wise, these came out a tad sweet for my liking. But Pioneer woman recommends adding sugar, which you could leave out. They also use more butter than any other method I tried. The final taste and texture, however, would be great for French onion soup.
Note: I do recommend doing some occasional stirring, just to ensure the onions heat more evenly. And you shouldn’t expect to get the same kind of browning you do in a skillet. It won’t happen. But the tradeoff in active cooking time may be worth it.
Method: Roasting in the Oven
Cook time: 45 minutes
Melissa D’Arabian at Food Network has this method for roasted onions with balsamic vinegar, which essentially caramelizes them in the oven. D’Arabian calls for quartering the onions instead of slicing them, which yields a much bigger bite — and they look different. But the resulting onion is so similar in texture and flavor that I don’t see using these in any way other than as caramelized onions.
If I made this again, I’d try slicing the onions much thinner. But after quartering them, I tossed the onions with oil, sugar, salt, pepper, and a few splashes of balsamic. Then roasted them in a 350-degree oven, in a heatproof skillet, covered with foil for the first 20 minutes, then uncovered for another 20.
At that point, the color was too light, so I added another five minutes under the broiler. The onions came out soft and brown and tangy-sweet. They would be great for grilled cheese or frittatas, but weren’t quite as cooked through as I would have wanted. However, the cleanup was much easier because you don’t get that intense buildup of fond (the bits of food that stick to the bottom of a pan) as you do over a burner.
Method: Instant Pot
Cook time: 40 minutes
I will admit that I love my Instant Pot, and I have made some fantastic things in it, including cauliflower, chili, and lamb rogan josh. So I was excited about the possibility that the pressure-cooking method Martha Stewart recommends could really be the secret to quick caramelization. The recipes says it takes 25 minutes total, including five minutes at high pressure.
But as soon as I opened the lid, I saw that the onions were overcooked and mushy. I’ve read recipes that call for 20 minutes of pressure, and I cannot imagine what you’d get with those.
The method suggests draining the excess liquid and sautéing for three to five minutes, which I did. But it did not help. The onions continued to be a wet, mushy mess, and I gave up after 20 minutes.
If you want really well-cooked, soft, mushy onion with very little caramelization, you might enjoy this version. I did not.
Method: Adding a Touch of Baking Soda
Cook time: 45 minutes
Most caramelizing recipes start the onions dry or with butter, but this one uses water in a covered pan to steam and instantly soften them. This prevents early charring, too. Once the water evaporates, you’re instructed to reduce the heat to medium-high and use a spatula to press the onions evenly into the pan, wait 30 seconds, then scrape up the fond (the brownish residue in the bottom of the pan) and redistribute the onions and repeat. This replaces stirring and seems effective, although it’s tiresome to do. And while they claimed you could caramelize the onions “in record time,” it still took me 35 minutes to get the perfect caramel color. As a final step, a baking soda solution is stirred in, supposedly to speed the chemical reaction that creates natural sugars in the onions.
Results: This Is the Winner!
I’m no chemist, but the resulting caramelization really was perfect, in my opinion, with just the right amounts of sweetness and browning. And while it wasn’t any faster, the change from constant stirring to only moving the onions every 30 seconds gave me at least a little more time to walk away and attend to other kitchen tasks without burning anything. This method, which yields the tastiest results for the effort involved, is my choice.