Caramelized Onions are a sweet and savory staple which can be used in countless recipes for burgers, steaks, chicken, dip, and so much more! Thinly sliced onions are sautéed in oil and butter until golden-brown and rich in flavor. While not a quick fix, this easy and classic recipe is well worth the wait!
There are few things more addictive than a skillet of beautifully caramelized onions.
Oftentimes, I find their sweet and savory flavor to be the PERFECT accompaniment to bring a recipe to the next level. Whether as a topping for a steak or a burger, mixed into a quiche, or even serving as the base to a rich French onion soup, they never disappoint.
While it can be tempting to try and quickly whip up caramelized onions, there’s simply no replacement for the rich depth of flavor that comes with a little time and patience.
By allowing pan-fried onions the time to fully release their natural sugars and to brown all the way through, you can be assured that their flavor will far surpass that of any shortcut.
So while this isn’t a technique which can be done last minute, it is still a super easy way to add a rich, savory, buttery flavor to your favorite recipes!
Ingredients
One of the best things about this cooking technique is how few items it actually takes. The simple ingredients you need to make this caramelized onions recipe include:
- Onions. Sweet onions like Vidalias are the best type to caramelize, for their high natural sugar content. Any other variety will work too, but may need to be supplemented with a pinch of sugar to reach the desired sweetness level.
- Oil. Because of the relatively low temperature at which caramelization occurs, any type of oil may be used, regardless of smoke point. A more mildly flavored oil, like vegetable or avocado oil, is recommended in order to avoid overpowering the sweetness of the onions.
- Butter. A high-quality butter is added toward the end of cooking, to provide an extra layer of richness and flavor. This may be omitted or substituted with vegan butter for a dairy-free diet, or with ghee for a Paleo or Whole30 diet.
How to Make Caramelized Onions
The basic steps for making caramelized onions are as follows:
Slice the Onions
The thinner the onions are sliced, the more quickly they will caramelize. For an ideal balance between cooking time and keeping the onions from falling apart as they cook, they should typically be sliced about ¼ inch thick.
For more information, learn how to cut an onion here.
After slicing, any individual layers of the onions still stuck together should be separated from each other. This enables them to have even contact with the skillet and the heat so they cook at similar rates.
Prep the Skillet
Heat the oil in a large stainless steel skillet over medium-low heat for several minutes, then add the onions. Stainless steel works best because it conducts heat more evenly than a non-stick skillet, and allows the onions to develop that beautiful browning over time.
At this stage, a pinch of salt can be added, to taste. If done early, this will help to draw moisture out of the onions and allow them to brown more thoroughly, giving them more flavor in the process.
The onions should be sizzling, but not so hot that they immediately begin browning, otherwise they’ll burn before they have a chance to caramelize. If it looks like they’re starting to cook too fast, simply lower the heat, add a couple tablespoons of water, and scrape any browned bits off the bottom of the pan and into the onions.
Cook Low and Slow
Cook the onions for 40-50 minutes, stirring occasionally. Once they have begun to soften, stir them every 3-5 minutes. This gives them enough time early on to kickstart the cooking process without burning later.
At the 30-minute mark, when the onions have turned a light yellow color, add the butter and stir to combine. This allows the onions to soak up that extra bit of fat and salt from the butter, amplifying their flavor without giving the butter time to burn.
Continue cooking as directed until they have reached a deep golden brown and the ideal sweet, savory taste. Monitor them closely at this point, as they could burn easily.
A small pinch of salt or sugar may also be used here, to further highlight the sweet and savory flavors, to taste.
Meal Prep and Storage
- To Prep-Ahead: Onions can be pre-sliced and stored in an airtight container in the fridge for up to 3-5 days.
- To Store: Leftovers may be stored in an airtight container in the fridge for up to 3-5 days.
- To Freeze: Leftovers may be stored in a freezer-safe container or freezer bag for up to 3 months. An ice cube tray or muffin tin can also be used to make individual portions before freezing.
- To Reheat: When frozen it is recommended to put the onions in the fridge to thaw at least an hour ahead of use. Once thawed, the onions can be reheated over low heat in a skillet, or in the microwave for 30 seconds at a time until warmed through.
Dietary Modifications
The recipe you’ll find below is already gluten-free, vegetarian, keto, Paleo, and Whole30 as written. Here are some adjustments and substitutions you can make to help it fit your other dietary requirements:
- Dairy-Free/Vegan: Omit the butter, or replace it with a vegan butter alternative.
- Reduced Sodium: Use an unsalted butter, and/or omit the salt entirely.
FAQs
Sautéed onions spend a lot less time on the heat, softening up and browning a small bit, while still retaining some firmness and sharpness of flavor. Caramelized onions cook for much longer, turning very soft and sweet as they brown throughout and bring out the onion’s natural sugar content.
Sweet varieties are the best onion to use when caramelizing, due to their naturally high sugar content. Vidalia onions are recommended, as they can be easily found at most grocery stores, but yellow onions are a good second best.
Making sure your heat is low enough that it does not scorch the onions, but hot enough that it cooks them, is the most important part of the caramelization process.
If you happen to burn some of the onions, you can save them by adding a few tablespoons of water to the skillet to deglaze it. Scrape the bottom of the skillet to remove any loose bits or pieces, mixing them in with the onions, and continue cooking as directed.
This varies depending on factors like how thin the onions are cut, the heat of the pan, whether any shortcuts are used, and more. Generally, however, it should take from 45-60 minutes to get a pan of thoroughly, naturally caramelized onions.
No. Adding sugar will not speed up the caramelization process of onions, but it will make them slightly sweeter.
To reduce the cook time by about 10 minutes, add ¼ cup of water to the skillet full of onions, cover with a lid, and cook over medium heat for 10 minutes. This speeds up the phase of simply softening and cooking the onions, so that they can begin browning quicker. Once softened, uncover the onions and continue cooking them as directed for an additional 20-30 minutes, or until caramelized.
Additionally, a pinch of baking soda can be added to the onions once softened, to help encourage browning. This may change the texture of the onions, however.
Expert Tips and Tricks
- Select steel. A large stainless steel skillet is the ideal tool for caramelizing onions, because they conduct heat the best and help food brown easier than a non-stick pan.
- Give them room. Use a big enough pan that the onions aren’t crowded before they’ve started shrinking down, to ensure they all cook at the same rate.
- Use more than butter. While butter adds a lot of amazing flavor to caramelized onions, it tends to burn, so a normal cooking oil should be used for the initial cooking process.
- Quicker caramelization. A pinch of baking soda added to the onions can help them caramelize faster by encouraging browning, but remember that doing so will break them down and give them an almost jam-like consistency.
- Remember to deglaze. There’s TONS of flavor packed into the brown bits at the bottom of the pan, so be sure to deglaze with water, stock, or even alcohol for a bit of extra flavor.
Make it a Meal
This sweet delicacy is most often known for topping burgers or accompanying a juicy piece of steak, like a filet mignon (along with Sautéed Mushrooms!)
There are also quite a few other dishes that can be taken over-the-top with the addition of the rich, buttery flavor these onions bring to the table:
- Salmon Burgers
- Butternut Squash Pizza
- Honey Balsamic Chicken
- On a baguette with Tomato Bruschetta
How to Caramelize Onions
Caramelized Onions are a sweet and savory staple which can be used in countless recipes for burgers, steaks, chicken, dip, and so much more! Thinly sliced onions are sautéed in oil and butter over medium-low heat for 40-50 minutes, until golden-brown and rich in flavor.
Ingredients
- 2 lbs. sweet onions about 4-5 small onions
- 2 tbsp. olive oil
- 1 tbsp. butter
- ½ tsp. salt to taste
- sugar optional*
- water optional*
Instructions
-
Thinly cut onions into ¼-inch slices.
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Add olive oil and onions to a large stainless steel skillet over medium-low heat.
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Cook onions for 40-50 minutes, stirring every 3-5 minutes.*
* (In the beginning you can wait a little bit longer between stirs. Towards the end you will want to keep a close eye on the onions, to prevent burning.)
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After about 30 minutes, the onions will start to become a light yellow color. Add butter and stir to combine.
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You’ll know the onions are done cooking when they reach a caramel color and have a natural sweetness to them.
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Serve caramelized onions with your favorite filet mignon, baked chicken, or recipe of choice.
Recipe Video
Recipe Notes
Meal Prep and Storage
- To Prep-Ahead: Onions can be pre-sliced and stored in an airtight container in the fridge for up to 3-5 days.
- To Store: Leftovers may be stored in an airtight container in the fridge for up to 3-5 days.
- To Freeze: Leftovers may be stored in a freezer-safe container or freezer bag for up to 3 months – an ice cube tray or muffin tin can also be used to make individual portions before freezing.
- To Reheat: Depending on storage method and intended use, when frozen it is recommended to put the onions in the fridge to thaw at least an hour ahead of use. The onions can be reheated over low heat in a skillet, or in the microwave for 30 seconds at a time until warmed through.
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