How to Caramelize Onions

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Caramelized onions are onions that have been slowly cooked to develop their flavor. Here's how to caramelize onions

Essentially the natural sugars break down in the onion, leading to rich and sweet onions that are almost jammy. They're a welcome addition to so many recipes - but especially famous in French onion soup and burgers.

I'll show you how to make the best caramelized onions as a home cook, how to freeze them for future use and answer all your FAQs.

Jump to:

• Why You Should Make Caramelized Onions
• Ingredients
• Instructions
• FAQs About Caramelized Onions
• Recipes with Caramelized Onions
• Storage
• Tips for Making this Recipe
• Caramelized Onions

Why You Should Make Caramelized Onions

This caramelized onion recipe does take a commitment to a cooking process of about 45 minutes to get a great caramelized onion, but it is so worth it!

The flavor is phenomenal. They have a deep, sweet flavor and they add a really wonderful depth to so many recipes. It's one of the best ways to enjoy onions.

I love to make a large batch of caramelized onions, freeze them, and use them over several weeks.

Ingredients

Here's all you'll need to make the best onions!

• Yellow Onions
• Butter
• Red Wine Vinegar
• Kosher Salt

See the recipe card for ingredient amounts.

Instructions

Slice your onions in half. Remove at least two layers of the outer skin/papery peel. Remove any green sprouts or soft parts.

Using a sharp chef's knife cut your onions into thin slices.

Heat a cast-iron skillet or other large skillet over medium heat. Once hot, add the butter and allow it to melt.

Add the sliced onions and toss them to coat with the butter. Sprinkle the salt on top and toss them again. 

Allow onions to cook for 25 to 45 minutes, depending on the caramelization level you want. 

25 minutes will be browned and 45 minutes will be caramelized.

Stir occasionally, with a wooden spoon, to make sure they aren't burning or sticking to the bottom of the pan. You can deglaze the pan with a little water if your onions are burning.

If you are getting too many crispy brown bits too quickly, reduce your stove to medium-low heat.

Remove onions from heat and season with red wine vinegar. 

Use immediately or freeze for up to 3 months. 

FAQs About Caramelized Onions

There are so many great questions about caramelizing onions. It's a simple process but there are some important things to know!

Let me know if you have any other questions in the comments.

Caramelized Onions vs. Sautéed Onions

Caramelized onions are cooked at lower heat for longer than sautéed onions (or browned onions).

Sautéing onions at medium-high heat for a few minutes is essentially just frying them. It develops good flavor quickly. Caramelization takes much longer and develops a deeper, more aromatic flavor.

What onions do you use for caramelized onions?

You can caramelize any type of onion, but the most commonly used (and most versatile) are yellow onions.

Sweet onions (vidalia onions) and red onions are delicious caramelized though, so don't be afraid to experiment.

Do you use salt to caramelize onions?

Yes, you'll definitely want to add salt to your caramelized onions - as soon as they go into the pan. This helps the flavor develop and tenderizes the onions quickly.

Do you cover onions when you're caramelizing them?

No, there's no need to cover your onions while you're caramelizing them. It won't noticeably speed up the process either.

What do you do with caramelized onions?

Caramelized onions are most notably used in patty melts, cheese steaks, and French onion soup, but they can be used in so many ways!

Add them to salads or sandwiches, use them as a pizza topping, add them to pasta sauce, or use them as a topping for canapés.

Why are my onions not caramelizing?

If your onions aren't caramelizing it could be one of three issues - they haven't been cooking for long enough, your pan isn't hot enough, or you have too many onions in your pan.

It takes at least 20 to 25 minutes to see some caramel color on your onions. It's likely that your onions just need more time.

If it's been over 40 minutes and you aren't seeing results, turn the heat up! Also, you can have several cups of onions in your pan but it shouldn't be heaping.

Are caramelized onions bad for you?

No, caramelized onions are not bad for you! Onions are good for you whether they're raw, cooked, or caramelized.

The caramelization process reduces the onion, and with this recipe, we use minimal fat and a small amount of salt. Onions are low in calories, a good source of fiber, and have no fat.

Can you freeze caramelized onions?

Yes, you can freeze caramelized onions. Allow them to cool before putting them in an airtight container. We like to freeze them in zip-top bags.

Recipes with Caramelized Onions

You can use caramelized onions in so many delicious recipes! Here are some of our favorite recipes with caramelized onions.

• Puff Pastry Onion Tart
• Warm Caramelized Onion Bacon Dip
• French Onion Meatball Skillet
• Caramelized Onion, Pancetta, and Feta Tart

Storage

Caramelized onions will last for up to 4 days in the refrigerator when stored in an airtight container.

To freeze the onions, allow them to cool fully and then put them in a gallon, zip-top freezer bag.

Flatten them and freeze them flat, so you can easily crack off pieces to use when necessary.

If you want to save them in smaller amounts, portion out tablespoon scoops into ice cube trays and freeze them. Once they've frozen into cubes, you can pop them out and save them in a freezer bag.

Tips for Making this Recipe

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Cooking Tips - Don't skip adding the pinch of salt to the onions right when they go into the pan. This helps tenderize them early on.

Substitutions - You can substitute olive oil for the butter or use half butter and half olive oil. You can substitute the red wine vinegar for balsamic vinegar or white wine vinegar if you'd prefer.

Recommended Tools - It's important to use the right pan for this recipe. I suggest using a cast iron skillet, a carbon steel pan, a dutch oven, or a heavy stainless steel pan for this recipe. I don't recommend using a non-stick pan.

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