Learn how to make caramelized onions perfectly every time! Rich, sweet, and deeply golden brown, they add complexity to pastas, soups, and more.
A few weeks back, I was making caramelized onions for this French onion dip, and Jack wandered into the kitchen for lunch. Usually, after he makes himself a sandwich, he heads straight back to his office, but that day, he lingered in the kitchen. “I should go work,” he said, “But it smells so good in here.” Like roasted garlic, caramelized onions are one of those magical, powerhouse ingredients that can amp up the flavor in almost anything – dips, pastas, soups, you name it. They’re rich, silky smooth, and sweet, and, as Jack can attest, they smell fantastic too.
Luckily, caramelized onions are easy to make. BUT making them does take time. Don’t try to rush the process on a weeknight, when you’re looking for a quick, pantry-friendly topping for a pizza or veggie burger. Simply put, caramelized onions aren’t quick. It takes at least 45 minutes (and often over an hour) over low heat for the natural sugars in the onions to caramelize. Still, the time is totally worth it. Packed with irresistible umami flavor, caramelized onions add complexity to all sorts of savory dishes. If you like cooking, knowing how to caramelize onions is a must.
Caramelized Onions Recipe Tips
- Make the full recipe. If you’re going to spend an hour or so making caramelized onions, you might as well make a lot of them! Stored in an airtight container in the fridge, they’ll keep for a week. You can also freeze them for up to two months. I like to freeze caramelized onions in ice cube trays. That way, I can easily thaw enough for a single dish and save the rest for another use.
- Choose the right pan. I love non-stick pans for making pancakes and eggs, but they’re not the best pick for caramelized onions. Instead, I recommend using a cast-iron skillet. As the onions cook, a delicious fond will develop on the bottom of the pan. If you scrape it up and stir it into the onions, it will make their flavor even richer. Pan size also matters. It should be large and wide in order to allow moisture to evaporate as the onions cook. For 4 onions, you’ll need a 12-inch or larger skillet. For 3 onions, a 10-inch skillet works well.
- Turn up the heat at the end. For most of the cooking process, the heat should be low or medium-low to prevent the onions from burning before they have a chance to soften and caramelize. However, once they’re brown and tender, I like to turn the heat up to medium, stirring constantly and scraping up the browned bits from the bottom of the pan, to get a little extra caramelization before I take them off the heat.
How to Caramelize Onions
My method for how to caramelize onions takes time, but otherwise, it’s really simple. Here’s how it goes:
First, slice the onions. Aim for the slices to be as even as possible so that they cook at the same rate. Before you add them to the pan, separate the onion layers.
Next, sauté! Heat olive oil (I use 2 tablespoons for 4 onions) in a large cast-iron skillet over medium heat. Add the thinly sliced onions and cook for 5 minutes, stirring frequently, until the onions soften.
Once all the onions have softened, reduce the heat to medium-low and continue to cook, stirring every few minutes. If the onions start to burn or stick to the bottom of the pan, reduce the heat to low. You could also add a splash of water if the pan starts to dry out.
It will take 50 to 80 minutes for the onions to get deeply brown, soft, and caramelized. The exact timing will depend on the size of your pan, the size of your onions, and the heat of your stove.
When your caramelized onions look like the ones in the photo above, they’re ready to eat! You’ll find all kinds of ways to use them, but here are a few of my favorites to get you started:
- In dip! They add delectable sweet and savory flavor to this French onion dip.
- In soup. Rich, savory French onion soup is a classic for a reason.
- As a burger or sandwich topping. Pile them onto a veggie burger or portobello mushroom burger, or add them to your next grilled cheese sandwich.
- With eggs. Fold them into an omelet or add them to a frittata. They’d also be fantastic in these single-serving frittata muffins!
- In pasta. Stir them into a simple roasted vegetable pasta, pesto pasta, or classic mac and cheese. They’d be yummy in this creamy vegan pasta or vegan mac and cheese, too!
- On pizza. Once you try caramelized onions on pizza, you won’t look back. Pile them onto my cast-iron skillet pizza or a homemade pizza made with any toppings you like.
How do you like to use caramelized onions? Let me know in the comments!
- Heat the oil in a 12-inch cast iron skillet over medium heat. Add the onions and sauté for 5 minutes or until starting to soften.
- Add the salt, reduce the heat to medium low and cook for 50 to 80 minutes, stirring every few minutes, or until the onions are very soft, golden brown, and caramelized. The timing will depend on the size of your onions and the heat of your stove.
- If at any point the onions start to stick to the bottom of the pan, reduce the heat to low. If the onions aren’t deeply brown after 50 minutes and you’d like to speed things up, you can turn the heat higher to get more caramelization. Stir continuously to prevent burning.