Ask the Experts: How to Caramelize Onions?

Q: I've tried making caramelized onions a few times at home, but they never turn out like the onions I've had at restaurants. What am I doing wrong?

A: Caramelized onions aren't complicated, but there are some do's and don'ts that can make or break them. These basic guidelines on how to make caramelized onions should help.

First and foremost, caramelized onions require patience and attention. They can take anywhere from 30 minutes to an hour or more. You'll need to scrape and stir every few minutes for most of the process, and monitor even more closely toward the end. Don't get impatient or fall for "get caramelized quick" schemes.

Second, cook caramelized onions over medium heat or lower. If you crank up the heat, you'll end up with sautéed or fried onions. (Which are also delicious, but they aren't caramelized.)

We recommend using a stainless steel pan for several reasons. It responds to temperature changes quickly, so you can turn the heat down and prevent your onions from getting crispy (or worse, burning). Even better, stainless steel creates those delicious browned bits called fond. Scrape them from the bottom of the pan with a spatula and stir them into the onions.

Cast iron works too, but the drawback is that it's not as responsive to temperature changes. You run the risk of overcooking your onions. While it's possible to caramelize onions in a nonstick pan, they won't be nearly as good. Fond adds a key flavor element, but fond doesn't form on a nonstick surface.

Be sure you use a pan that's large enough for all the onions. Too many onions will result in steam, which condenses into water and prolongs the process. Caramelizing onions takes long enough; don't crowd the pan and make it take even longer.

You can use butter or oil, or a combination of both. Butter adds more flavor to caramelized onions, but it has a lower smoke point than oil. Contrary to popular wisdom, mixing butter and oil does not raise the smoke point. All the more reason to go low and slow when caramelizing onions, in our opinion.

Regardless of which fat you choose, go easy.  Bon Appetit sums up why: "The more fat in the pan, the more the onions will fry rather than soften."

Finally, use wine or balsamic vinegar to deglaze the pan. That simply means to add some of either liquid to dislodge all the fond from the pan and mix it into the onions. It adds to the flavor and helps clean up your pan.

Now you know how to make caramelized onions properly. Let us know how they turn out next time!