How To Caramelize Onions That Won’t Brown: Best Tips

Caramelized onions are the perfect topping on burgers, Mediterranean dishes, or onion soup. But they can be a struggle, as anyone who has cooked them will know. Often they won’t brown as you want, so I did some research to find out how to cook them perfectly.

Caramelizing onions until brown takes longer than expected and requires some patience – at least 30 to 60 minutes. Using a large heavy-based pan, slicing evenly, using enough oil, and stirring periodically will help the caramelization process.

Deglazing sticky bits with balsamic vinegar, bourbon or stock is another tasty way to get the most out of your onions.

Sauteeing onions is one of the ways to mellow their raw onion flavor. But there can be several reasons why your caramelized onions won’t turn brown. Let’s look at some top tips to ensure you don’t have this problem. Get your onions, saucepan, and patience ready!

How Long Does It Take For Onions To Caramelize?

Onions will start browning in the pan in 10-15 minutes but will take 30-45 minutes until they release enough sugars to start caramelizing.

You need to eye your onion mixture and go with your gut feel. 

When it comes down to the amount of time you will need to caramelize your onions, it’s good to remember it’s not a five-minute process. The deep flavors you are after only come with time.

With cooking, your onions will change to transparent, then golden, and finally develop a caramelized color and taste. Typically, this process can take anywhere from 30-60 minutes, depending on the heat of your pan and the number and type of onions.

If you’re not patient enough, your onions won’t turn brown. They may turn a faint golden-brown color but not the deep caramelized brown your aiming for. 

The top tip regarding how long caramelized onions take is: to be patient. Don’t try and speed up the process as it is a long and delicate process to caramelize onions.

How High Should The Heat Be To Caramelize Onions?

Start with a medium-high heat to add some color to the onions but then reduce the heat to medium-low. This prevents the onions from burning in the later phases but continues caramelization.

Technically, caramelization only happens at temperatures 310F/155C or higher. This is a fairly low and slow process. It’s important to bring your onions to 310F/155C, then keep them at this temperature and not go too high because they might burn.

The secret is your onions must be on a low enough heat for a long enough time to release their natural sugars. Medium heat, together with the natural sugars from the onions, will give you that caramelized brown.

I explored whether you need sugar to caramelize onions in another post, the short answer is you don’t, but check out that post if you are struggling to get them caramelized.

Don’t be tempted to try to turn up the heat to speed up the process as they can go black, crisp, and burnt. 

But if you have been standing in front of the stove and your onions have not changed color, you may want to increase the heat of your pan slightly. 

Should You Drain Liquid When Caramelizing Onions?

Drain or cook off excess liquid from caramelizing onions. It’s acceptable to have a little liquid in the pan while sauteeing as the onions are soft and moist. Keep enough oil in the pan to prevent burning.

Crispy fried onions are different – you want dry onions cooked in hot oil so that they get very brown and very crisp. Caramelized onions are slightly different as they aren’t so crispy at the end.

You want the onions to release their natural juices and sugars as this will enable them to caramelize. What you don’t want is excess water as they will steam instead of brown. It’s OK to have some liquid lightly cover the bottom of your saucepan. Any excess liquid can be drained.

After the onions have cooked off a bit, you might need to add some more oil to ensure they don’t get too dry and stick to the pan. A splash of water (or balsamic vinegar, bourbon, etc) can deglaze the pan to release flavor.

Deglaze the pan to release extra flavor

Do You Cover Onions When Caramelizing?

It’s a good idea not to cover onions when caramelizing so that you can stir them periodically. Covering the onions keeps moisture in to steam them and prevents you from monitoring the browning.

Covering a pan with warm content causes condensation and steam. If you want dryer and crispier onions then you should definitely remove the lid. Note that your onions will burn quicker without any liquids so need stirring.

Onions can burn if left alone, but onions that are too watery will never turn brown and caramelize. 

My tip is to be attentive and watch the onions so that they don’t burn. Equally, you don’t want to stir too much as they will never brown.

How Often Should You Stir Caramelized Onions?

Caramelizing onions should be stirred enough so they don’t burn. In the beginning, this might be every few minutes, but near the end when they are golden they will need constant stirring to prevent burning.

By now, you know that nothing is hands-off when it comes to caramelizing onions! If you don’t stir the onions frequently, some parts will brown more than others, or pieces of onion stuck to the side of the pan will burn.

Stirring too frequently can also be a problem in the beginning because the onions need a chance to build some color. If they are constantly moved then they stay translucent longer. Try keeping an eye on them for the best results.

When the onions are well on their way to being fully browned, they can burn within seconds of leaving them. So I recommend staying with them and stirring frequently. Burnt onion is black and tastes bitter.

How Do You Know When Caramelized Onions Are Done?

Judge the color and evenness of the browning. They should be colored all over, with deeper colors giving more intense flavors depending on how strong your recipe requires.

French onion soup typically requires less browning than strongly caramelized onions you might use for burger toppings. Match the intensity with other ingredients in your dish – beef can obviously take some strong condiments.

Don’t give up halfway through the process when your onions have reached a blonde, brown color. This is the desired color for French onion soup, not for caramelized onions. 

When your caramelized onions are done, they will be a deep and dark brown with a sticky consistency. Not sugary, just sticky, almost like caramel; hence we call them “caramelized onions.”

Golden Onions
Deep caramel onions

Tips For Caramelizing Onions

Caramelized onions are one of my favorite condiments to prepare when making homemade burgers. Through the years, I have learned some tricks to get that perfectly brown caramel color.

  • Use olive oil as a replacement for butter; olive oil does not burn as quickly as butter. 
  • When adding your onions to your olive oil on medium heat, add some table salt. Salt extracts the natural juices out of the onions. 
  • Use the biggest heaviest pan you have, even if you’re only preparing a small number of onions. Using a bigger pan will allow the heat to spread evenly.
  • If your onions are dry add a teaspoon of water/vinegar/alcohol to deglaze.
  • Use more onions than you think – they wilt down a lot.


Hopefully, you now know how to caramelize onions that won’t brown for you. Caramelizing onions takes practice and patience. Usually, you just need some extra time to get that deep color you want.

Use these tips the next time you struggle to get your caramelized onions brown. Remember your gut feeling may be the best guideline when applying heat and stirring.

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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