5 Mistakes to Avoid When Making Caramelized Onions

updated May 1, 2019
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(Image credit: Emma Christensen)

If you’ve ever tasted caramelized onions, then you know how truly magical they are. These slow-cooked, rich-tasting slices of onion have the power to completely transform anything and everything they touch. But if you’ve ever made them, you know the process can be tricky.

While it’s not particularly difficult, there are a few potential pitfalls along the way that can totally derail a really good batch of caramelized onions. Make sure you stay on track by avoiding these common mistakes.

1. Slicing the onions too thin.

When eaten raw, super-thin onion slices are ideal, but it’s a different story when you caramelize them. When onions are sliced too thin, they run the risk of burning very easily.

→ Follow this tip: The onions should be sliced thin, but not too thin (also not too thick). It’s also important to cut the onion into evenly-sized slices.

2. Cranking up the heat too high.

Caramelizing onions is not an instant gratification process; they take a while to cook. It may be tempting to crank up the heat to speed the process along, but that’s the worst thing you can do; it only puts you more at risk for burning your onions.

→ Follow this tip: Caramelized onions require time and patience. They’re all about low, slow cooking. Stick to it and you’ll be rewarded. You can’t rush the kind of magic that caramelized onions bring.

3. Not stirring the onions.

Making traditional caramelized onions on the stovetop is not a set-it-and-forget-it project. Forget to stir the onions and you’ll find yourself on the fast track to unevenly cooked and burnt onions.

→ Follow this tip: Making caramelized onions is a hands-on task that requires your attention. For even cooking, and to prevent burning, it’s essential to check and stir the onions every five to 10 minutes.

And if you don’t feel like you’re quite up to the task, you can also try making caramelized onions in the slow cooker.

4. Not cooking the onions long enough.

It might be tempting to pull the onions off the stove as soon as they start to soften and turn golden-brown, but resist the urge. They’re not completely cooked yet — they need more time. Caramelized onions should be far darker than golden in color.

→ Follow this tip: Cook times will vary depending on the number of onions you’re cooking and the type of onion (its sugar content and age), but plan to cook caramelized onions for 40 to 50 minutes (at least) until they have a dark-brown, rich color.

5. Not deglazing the pan.

The final step in making caramelized onions just may be one of the most important, yet so many people neglect it altogether. As the onions cook, a sticky-looking film, which can easily be mistaken for burning (although it’s not), develops on the bottom of the pan. This is called the fond, and it’s where all the flavor sits.

→ Follow this tip: Deglazing the pan is the final, and crucial step in making caramelized onions. Use a liquid like wine, broth, or even water to release the fond from the bottom of the pan, and scrape and stir to incorporate it into the onions.

Is there anything we didn’t cover here? What are your best tips for making caramelized onions?