How To Make Caramelized Onions For Burgers (All You Need To Know)

The secret to making your burgers a hit is by mastering the art of caramelizing onions. Like any other craft, this one requires you to learn a few techniques, which we are sharing in this article.

The first thing to learn in making caramelized onions is slicing the onion thinly and lengthwise. Keep in mind that it’s best to have plenty of onion halves as the quantity of the slices is reduced once cooked. The main event is melting the butter in a saucepan on medium heat until it’s sizzling enough to stir the onions with it until they’re caramelized.

How long you’ll be stirring the onions in the pan is up to you. The longer the better for burgers. Now, read on as you need to know a few more things about how to make the perfect caramelized onions for burgers despite the simple steps above.

What Are Caramelized Onions?

Caramelized onions are often perceived as onions made with sugar. The process above did not cite any use of sugar, though.

This is because onions have their own sugar. It is when these onion slices are stirred with melted butter that their sugar caramelizes.

The heat induces the chemical process, browning up the onion slices the longer you stir the onions on the low to medium-heated saucepan. The onions also start producing a pleasant smell as they darken along the process.

How Do Caramelized Onions Taste? Are They Sweet?

Caramelized onions are sweet. The level of sweetness depends on how long you stir the onion slices on the heated saucepan.

The taste also varies depending on the onion type. Here are the following kinds of onions and their corresponding taste:

  • Yellow onions – The sweetness of caramelized yellow onions is more versatile than other onions. These onions also seem to be more natural when it comes to caramelization. They could be used for burgers, salads, and everything in between.
  • Red onions – Caramelized red onions have this deep dark color that produces such a great sweet taste. They are best used on pizza and salad. However, they are not guaranteed to go well with all the ingredients of a burger.
  • White onions – White onions are not commonly caramelized. They also produce a rich sweet flavor, but the other two onions develop more savory colors when caramelized.

What Onion Should You Use?

The best onion to use for caramelization is the yellow one, especially if you’re topping burgers with it. Despite being the most versatile of them all, yellow onions just have a stronger flavor compared to the rest.

The balance between the sugar components and astringent taste in these onions makes a unique sweet flavor. Who doesn’t want that game-changer of a topping for burgers?

How Do You Slice Them?

To ensure that you slice the onions thinly and lengthwise, here are the steps you have to follow:

  1. Slice the onion in half through the root end
  2. Use the tip of your knife to make a V-shape cut that will remove the root
  3. Put an onion half on your chopping board (root end is facing you)
  4. Start slicing it thinly and lengthwise about ¼” – ⅛” thick, starting at one side to reach the other (for uniform and properly sized slices)

Can You Make Them Ahead?

Yes, you can make caramelized onions ahead of time. In fact, they last up to a whole week when kept in a fridge. That means you can keep them around as a condiment.

Your leftovers can also survive that long to top another set of burgers. Just remember that re-heating them shouldn’t take as long as when you were still caramelizing them.

Can You Make Them Without Oil?

You can make caramelized onions without oil or even butter, although using oil or butter works just as fine. It’s just a matter of preference. The only difference is the process.

How to Make Caramelized Onions with Oil

  1. Slice the onions from root to tip as advised.
  2. Use olive oil (healthy option and brings out the flavors) and heat it with butter or just alone.
  3. Add the onion slices.
  4. Stir the onions for 30 minutes to an hour until cooked according to sweetness preference.

How to Make Caramelized Onions without Oil or Butter

  1. Slice the onions from root to tip as advised
  2. Use a dry saute pan and set it on high heat.
  3. Test the heat by sprinkling some water. If it’s easily absorbed, then it’s time for you to dump the onions into the pan.
  4. Let the onions sit there for a minute until they’re cooked. Do not stir them at all as letting the onion slices sit on the same spot will start caramelization naturally.
  5. Keep an eye out for the browning of the onions underneath. That’s the time when you add 2 tablespoons of vegetable broth and begin with stirring.
  6. From there, cook the onions for 2-3 more minutes.

Both methods for caramelizing onions bring out the rich flavor of the vegetable (yes, fun fact: onions are a vegetable). Some people just prefer having their caramelized onions made without any fat (without oil/butter).

How to Properly Deglaze the Pan After Caramelization?

Deglazing the pan after caramelizing onions is a crucial part of the operation. It is what mixes the wonderful browned flavors from the bottom of the pan into the onions.

Here are the steps to make sure all the necessary relish of the browned bits go back into the onion slices:

  1. Add 2 tablespoons of water, red wine, white wine, vinegar (balsamic is highly recommended), and broth into the saucepan. Take note that the wine, vinegar, and broth are optional but great at lifting all the savor back into the onions.
  2. When the liquid starts boiling, use a wooden spatula to scrape the browned pieces on the surface of the pan and stir them with the onions.
  3. Repeat this activity multiple times during the caramelization each time the bottom of the saucepan generates browned layers.

When Are Caramelized Onions Done?

The duration of the onions’ caramelization depends on how sweet you want them to turn out. The traditional process takes up to 20 minutes, despite how many recipes say 5 to 10 minutes is possible.

Physical changes in the onions can change between 5 to 10 minutes but that barely releases the sugars out of the slices. The maximum amount of time to produce the most delicately sweet caramelized onions is an hour.

Cook onions slowly until tender and translucent, about 10 minutes. Blend in the salt and sugar, raise heat to moderately high, and let the onions brown, stirring frequently until they are a dark walnut color, 25 to 30 minutes.

Authentic French onion soup recipe by Julia Child

That is a total of 35 to 40 minutes.

How to Speed up Making Caramelized Onions Process?

By now, you’re already familiar with how caramelization works – you use heat to release the sugars in the onions that make that amazing sweet flavor. So here are the specific ways you can speed up the process:

  • Cranking up the heat – High heat can quicken the caramelization of the onions if you’re making them with olive oil or butter. Just make sure to keep stirring the slices to prevent them from sticking and getting burned.

    Every 5 minutes, the onions will begin to brown so make sure to drop 2 tablespoons of water to deglaze the saucepan. You should also scrape the brown parts from the bottom into the onion slices every 2 minutes for 15 minutes.
  • Adding more sugar – Adding a tablespoon of sugar before pouring the oil or melting the butter in the pan will accelerate the process. The sugar will balance out the bitterness in onions fast so its natural sweetness can come out earlier than usual.

How Long Do They Last?

Caramelized onions can last up to a week if kept in the refrigerator as mentioned earlier. It can also survive up to three months if you freeze them.

So making plenty of caramelized onions in one batch is never a bad idea. That makes the craft friendly to burger joints that need to stock up on ingredients for long periods.

Final Tips

Now that we’ve educated you with the techniques you can use to master the art of caramelizing onions, allow us to polish a few things about them. First, you should follow the specific measurements cited above.

Precise quantities and sizes are a significant factor in the outcome of this art. For instance, the slices of onions can’t be too thin as they will burn easily.

The same goes for the amount of liquid ingredients you have to pour to make the procedure quicker or more successful. The sweetness and slight bitterness of the onions still have to come out naturally, so the goal should be to enhance the process instead of disrupting it.

Lastly, it’s imperative that you exercise patience throughout the caramelization of the onions. Like any other intricate procedure, the onions need enough time to soften and produce delicious tastes.

Scott Wagner

I'm Scott Wagner, one of the guys behind I am totally passionate about the world of Burgers and BBQ, especially when I have friends visiting my backyard during a summer sunny day! Here I decided to share my passion with you!

Recent Posts