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How to Caramelize Onions

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Caramelized onions are onions that have been slowly cooked to develop their flavor.

Essentially the sugars break down in the onion, leading to a sweet and rich flavor that's almost jammy. They're a welcome addition to so many recipes.

We'll show you how to make the best caramelized onions, how to freeze them for future use, and answer all your FAQs.

caramelized onions in a pan

Why You Should Make Caramelized Onions

It does take a commitment of at least 25 minutes to get a great caramelized onion, but it is so worth it!

The flavor is phenomenal. They have a deeper, sweeter flavor and they add a really wonderful depth to so many recipes. We love to make a large batch of caramelized onions, freeze them, and use them over several weeks.

caramelized onion ingredients

Some Frequently Asked Questions about Making Caramelized Onions

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

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

Caramelized Onions vs. Sautéed Onions

Caramelized onions are cooked at a low 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 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.

If you make a large batch, you can flatten the onions out to a 1/2 inch layer in a freezer bag. Freeze it flat and just break off however much you need to use whenever you need caramelized onions.

chopped onions
caramelized onions in a bowl

Recipes with Caramelized Onions

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

how to freeze caramelized onions

Tips for Making this Recipe

  • We suggest using a cast iron or carbon steel skillet for this recipe. Dutch ovens will work as well. We don't suggest using a nonstick skillet.
  • If you'd like you'd prefer, you can substitute olive oil for the butter or use half butter, half oil.
  • It's essential to salt the onions early, don't forget this step.
  • To freeze the onions, allow them to cool fully and then put them in a gallon, zip-top freezer bag. Flatten them and freeze flat, so you can easily crack off pieces to use when necessary.
Yield: about 2 cups

Caramelized Onions

caramelized onions in a pan

Here's how to easily caramelize onions for a deep, delicious flavor.

Prep Time 6 minutes
Cook Time 40 minutes
Additional Time 2 minutes
Total Time 48 minutes

Ingredients

  • 3 medium yellow onions, thinly sliced
  • 2 tablespoons butter
  • 1 teaspoon kosher salt
  • 3 teaspoons red wine vinegar

Instructions

  1. Heat a cast-iron or carbon steel skillet over medium heat. Once hot, add the butter and allow it to melt.
  2. Add the onions and toss them to coat with the butter. Sprinkle the salt on top and toss them again. 
  3. Allow onions to cook for 20 to 40 minutes, depending on the caramelization level you want. Stir occasionally to make sure they aren't burning.
  4. Remove onions from heat and season with red wine vinegar. 
  5. Use immediately or freeze for up to 3 months. 

Nutrition Information:

Yield:

10

Serving Size:

1

Amount Per Serving: Calories: 33Total Fat: 2gSaturated Fat: 1gTrans Fat: 0gUnsaturated Fat: 1gCholesterol: 6mgSodium: 231mgCarbohydrates: 3gFiber: 0gSugar: 1gProtein: 0g

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Denise Holahan-Miree

Friday 28th of May 2021

I love caramelized onions. I've never ut them in the freezer. I'm just wondering if they still have the same flavor after being frozen.

Emily

Friday 28th of May 2021

They keep their flavor surprisingly well! I've been using the latest batch I made for about three months and I just crack off a few inches to throw in soups and pasta. It's worked great!

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