Do You Need Sugar For Caramelized Onions?

When making caramelized onions, many people think you need sugar to caramelize them, but don’t realize onions contain natural sugars that aid the process of caramelization. What you do need are time and patience.

You don’t need to add extra sugar to caramelize your onions; you only need more time to allow the process to caramelize onions completely, allowing the natural sugars to break down and release. The process takes between forty-five minutes to an hour for the onions to caramelize properly.

Some recipes suggest adding sugar, but this may produce overly sweet onions that do not have the rich, deep flavors of naturally caramelized onions.

Caramelizing onions is a slow process where thinly sliced onions are fried in a good quality fat over low heat to sweat the moisture out of the onions. Following the proper steps and using the right equipment will help you caramelize onions easily. See some of my tips below.

How Do You Get Onions To Caramelize?

Onions are naturally sweet, some more than others, so the idea that you must add sugar to caramelize onions is a misconception. The natural sugars from the onion are sufficient enough to do the job.

Their high water content requires a longer sweat time for the onion to start caramelizing. 

You can use all onions for caramelizing but sweeter onions are a good choice as they contain more sugar than other more astringent onions, so choose these if possible:

  • Sweet onions – (Vidalia, Walla Walla, Texas sweet onion)
  • Yellow onion
  • White onion

Don’t get tempted to crank up the heat. Instead, give the onions time and follow these simple steps to ensure you create tasty, sweet caramelized onions with deep flavors and rich textures.

Slice Your Onions Evenly

Slicing your onions 1/8 inch is a good size for caramelizing onions. Heat your pan over medium-low heat so as to not burn the onions. Think twice before using diced onions as they shrink considerably.

Add Good Quality Olive Oil Or Butter

The amount of fat you add to your pan will also determine the results of the end product. The more fats you add to your pan, the more the onions will fry. A thin layer of fat will result in softer onions, while larger quantities of fat will result in more crispy onions.

Place Your Onions In A Thick Pan

The best pan to use is a thick-bottomed cast iron or stainless-steel pan. They retain the heat well and allow a constant and uniform heat dispersion to cook the onions evenly.

Don’t Crowd Your Pan 

Crowding your pan with too many onions can prevent them from caramelizing effectively; instead, use a bigger pan or caramelize your onions in batches. In general, two onions are sufficient for a 12-inch pan.

Allow The Onions To Sweat 

Sweating is integral to caramelization. It allows the onions to release their juices. Try making caramelized onions when you have something else to do in the kitchen, as staring at onions and occasionally stirring for an hour can be pretty dull. It’s tempting to remove them before they are appropriately caramelized.

Give Them Time

You must allow the onions to fry gently for at least forty-five minutes to one hour from when they hit the pan. The authentic, rich, deep caramelized flavors only start to come out once the onions begin to turn a deep brown.

Deglaze The Fond

When the fond (the brown bits) builds up on the pan, you can use some liquid to deglaze the pan. This is where all the deep, rich, savory flavors mix back with the onions to give it that extra depth. 

You can deglaze your pan with any liquid that will complement the dishes you add your onions to. Here are a few examples:

  • Water
  • Balsamic vinegar
  • Red or white wine
  • Stock or broth
  • Dry Sherry
  • Jack Daniels

Why Won’t My Onions Caramelize?

Reasons why the onions don’t caramelize:

  • They haven’t cooked long enough
  • Your pan is overcrowded
  • The pan is covered with a lid
  • Using the wrong type of pan
  • The heat is too low

Frying up onions for ten to fifteen minutes, as some recipes suggest, won’t yield caramelized onions – that only produces sautéed onions. You need at least 45 minutes of cooking – I explain this in my article on why your caramelized onions won’t brown.

Quick fixes never work, and that’s never been more accurate than when you have to caramelize onions.

Onions sweat and release juices while breaking down the sugar. These juices slow down the cooking time, so overcrowding your pan may prevent the onions from cooking.

Don’t cover your pan with a lid. This will prevent caramelization as it only adds to the moisture content of your pan, steaming your onions more than anything else. An open pan allows the juices to evaporate, leaving behind the fond in the pan that contains all the intense flavors from the onions.

Try to avoid non-stick pans. It would help if you instead used thick bottomed cast iron skillet. If you don’t have one of those, try a thick-bottomed stainless-steel pan.

Your heat also may be too low. The perfect temperature is medium-low, but keep an eye on the heat to ensure your onions don’t burn. Each stove is different, so you must play around slightly until you get the perfect temperature.

How Long Does It Take To Caramelize Onions?

Caramelizing onions is a long and slow process if you want the end result to give you that umami flavor everyone raves about.

On medium to low heat, you can achieve caramelized onions that turn a rich deep mahogany color within 45 minutes to 1 hour.

Some chefs turn the heat down to low and can show extreme patience by allowing them to slowly caramelize over 1½ to 2 hours, sometimes more, producing a jammy-styled caramelized onion. Dedication to drawing out the best flavors from the onion.

Do You Use Butter When Caramelizing Onions?

You need a good quality fat to achieve the desired outcome of mouthwatering, rich, deep flavors you can attain from slowly caramelizing onions.

Butter is a good option for caramelizing onions, but butter may burn onions quicker due to its lower smoke point.

A good quality virgin olive oil is another excellent option to fry your onions in, or you can use half and half. But, let’s be honest, adding a bit of butter makes everything taste better. So, combining the two gives you the benefit of higher smoke points with rich, creamy butter flavors.

More Frequently Asked Questions

Here are some more commonly asked questions that may help you during the process of caramelizing those perfect onions.

Do You Salt Onions When Caramelizing?

Once your onions start to saute and turn translucent, you can sprinkle a pinch of salt over the onion. Salt will make the onion sweat more, drawing out more moisture from the onion. 

Don’t add too much salt as you want the natural tastes of the sweat caramelized flavors to shine through in the end, and not an overly salty flavor.

How Often Should I Stir The Onions?

Don’t over-stir your onions. In the beginning when they are white they will need less stirring – every few minutes. Towards the end when they are darker, they require more frequent stirring and attention so they don’t burn. They are at a higher risk of burning when they are in this later phase.

Keep an eye on the heat and allow the onions to gently saute in the pan. This can take some trial and error to get the “sweet” spot of caramelization.

What Goes Well With Caramelized Onions?

Caramelized onions are no longer restricted to cheeseburger toppings. Their intensely rich flavors can also be the center of the dish served with soft folded scrambled eggs or paired on a crispy slice of rye toast with a serving of goat cheese, creating a symphony of flavors on the palate.

They also make delicious dips and condiments that can be added to dishes for an umami flavor to compliment pasta, stews, soups, or braises.


Hopefully, you now know you don’t need to add sugar to make caramelized onions. Caramelizing onions should never be rushed if you want soft textures with sweet flavors without sugar.

When onions are correctly caramelized, their natural sugars are released into the pan, adding to the caramelization. The flavors instantly upgrade any savory dish, no longer reserved for hamburgers.

Have any questions? Ask me in the comment section below and I’ll get back to you.

Tom Hambly

Tom Hambly is the founder of Boss The Kitchen. With a background in cooking and building websites, he enjoys running this site to help other cooks improve. About Tom Hambly.

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