How To Caramelize Onions


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The best way to caramelize onions is with patience. And time. You can’t rush the process or you will burn them. There is nothing better than rich perfectly caramelized onions.

The big secret to caramelizing onions therefore, is patience and time.

Easy Caramelized Onions in an iron skillet.

What are the best onions for caramelizing?

You can caramelize any onion variety but my favorite are sweet onions such as Vidalia. The only problem is Vidalia onions are not available year round. Feel free to use any variety that’s available in your market. The technique will be the same.

I have caramelized red onions on occasion and by doing so it softens the flavor. Raw, Bermuda onions can have some heat to them. That goes away when you caramelize them.

Raw onions on a bamboo cutting board.

What does it mean to caramelize onions?

It means you are cooking them slowly to bring out the natural sugars. By doing this you take away the raw pungent bite of the onions. An intense flavor comes through and the onions become transluscent and soft.

In my opinion there are different levels of caramelization. Unless I’m making an onion jam, which would require a very dark caramelization, I like them transluscent and lightly golden with a bit of caramel color. 

I don’t want to use the word crunch but they do have some texture to them. 

When making an onion jam, you want the onions a very caramel color and completely shrunk down.

Sliced onions in a cast iron skillet.

How long does it take to caramelize onions?

This is a REALLY difficult question to answer. It’s a slow process that should not be rushed. Rushing will only produce burned onions and no one likes them.

I know you don’t want to hear this but for the perfect caramelized onions you need, at minimum, 45 minutes to 1 hour. Plan ahead.

Because they don’t need to continuously be stirred just keep them on the stove and work on other aspects of dinner, such as making the burgers, etc.

The best tips for slicing onions

For perfect sauteed onions every time these are my best tips:

  • Use fresh onions, if they’ve been around too long and begun to sprout, choose a different onion.
  • Use a sharp knife when slicing onions. You want nice clean cuts.
  • The onions need to be uniform in size. When slicing, keep them all the same width. Experts say 1/8 of an inch but I personally like them thicker, more like 1/2 an inch.
  • To keep from crying, place a wet paper towel at the edge of your cutting board. Like magic, it will keep you from crying.

Caramelized onions in a cast iron skillet with a wooden utensil.

Should I use butter or oil when sauteeing onions?

A combination of butter and oil is really best. Butter has a low smoke point and if you don’t add oil, the onions can burn. 

Confession: I sometimes only use butter, but I’ve been making caramelized onions for so many years I don’t burn them.

If you want to caramelize onions, I’d suggest starting with a mixture and once you’ve mastered the techinique, decide if you want to try using only butter.

I use a neutral oil such as canola or vegetable. I want to taste the sweetness of the onions.

Some prefer olive oil, which is perfectly acceptable since you caramelize onions over lower heat, but I don’t care for the flavor it adds. Olive oil can be overpowering.

To Salt or Not To Salt?

Salt… is it necessary? No so if you’re on a low sodium diet, no need to use it. Adding a teaspoon or so of salt will make the onions sweeter. Use a little more salt if you have lots of onions.

If you choose to add salt, it’s important to do so at the beginning of cooking.

Some people like to add sugar to add to enhance the onion’s natural sweetness. I don’t find that necessary, especially if using a sweet onion variety.

Onion Nutrition

Onions are so flavorful but are low in calories, fat-free and cholesterol-free, before the butter of course! The National Onion Association has a wealth of information on their website. Did you know onions have vitamin c, folate, and potassium, among other good things for you?

Can I add anything when caramelizing onions?

Absolutely! Some great flavors that go along with the onions are thyme and rosemary. They are hearty herbs that will stand up to the longer caramelization time of the onions.

How can I use caramelized onions?

Honestly, the possibilities are endless. I love serving sauteed onions along side steak and have even been know to include them in my chicken noodle soup. You would not believe the flavor they bring to the soup!

I also love to top burgers with them, especially my bacon and cheddar smash burgers. But then there’s the quintessential recipe that uses caramelized onions – French onion soup. A family favorite is a diner specialty of hamburger steak with brown gravy and onions.

How to caramelize onions Twitter image.

Then there’s pizza. You can also top homemade pizza dough when making pizza. This roasted garlic and chicken white pizza is a take on California Pizza Kitchen.

I often make this steak sandwich with caramelized onions for a weekend lunch. And, saving one of our favorites for last, these green beans with bacon and caramelized onions are a family favorite.

How to caramelize onions Pinterest image.

Caramelized Onions Recipe

Caramelized Onions

Use caramelized onions in many recipes.
5 from 21 votes
Prep Time10 minutes
Cook Time40 minutes
Total Time50 minutes
Course: Side Dishes
Cuisine: American
Servings: 1 /4 cup


  • 3 medium to large sweet onions Vidalia, Walla Walla, Maui, sliced in half-moons and separated
  • 1 tablespoon butter
  • 1 – 2 teaspoons sea salt


  • In a large skillet melt the butter over medium-high heat.
  • Once the butter is melted, add the onions and salt, stirring to combine. Keep an eye on the onions and stir occasionally.
  • Once the onions begin to soften, reduce the heat to medium-low.
  • Cook onions, stirring occasionally until they begin to turn golden brown and translucent.

Recipe Notes

The caramelizing process takes time and patience.

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  1. Caramelized onions have amazing flavor and would love it in my sandwiches and fries too! this is a great post explaining every detail about caramelizing onions. Wonderful post!

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