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This caramelized onion recipe cooks down onions until they are barely recognizable – in the best possible way! It’s a must-know skill for your kitchen arsenal. While caramelizing onions seems super simple – and it’s really not hard – there is some technique involved to making the best caramelized onions that are sweet and plump.
In this guide, I’ll cover everything from the basics of how to caramelize onions all the way to a multitude of ways to use them, and everything in between: the best pan to use, troubleshooting issues, tips and tricks, and more. Mastering this skill is a must-have for your cooking.
What Are Caramelized Onions?
Caramelized onions are onions that are simply slow cooked in butter or oil, until they are very soft and golden.
What do caramelized onions taste like?
They taste sweet – and they add a sweet and savory flavor profile to just about any dish (more on that below).
What is the difference between caramelized onions and sauteed onions?
Caramelized onions are cooked slowly, at medium heat and for a long time, allowing the natural sugars in the onion to caramelize. The result is much sweeter than sauteed onions.
Sauteed onions are cooked more quickly, typically over medium-high heat. The result is browning on the outside and a soft inside, but not caramelization.
How To Cut Onions For Caramelizing
You can cut onions in two ways – slicing or dicing. I personally prefer my caramelized onions sliced, so that they make luxurious ribbons when complete, but diced onions will caramelize, too.
To slice the onion:
- Peel the onion.
- Cut off the ends.
- Cut the onion in half.
- Place an onion half flat side down and slice to about 1/8 inch thickness, parallel to the cut ends.
- Repeat with the other half.
To dice the onion:
- Start by following the same steps above, keeping the slices together when slicing.
- Turn the sliced onion 90 degrees and slice in the opposite direction.
How To Caramelize Onions
It’s time to show you how to make caramelized onions! It’s super easy – but patience is key. Read the 2-step process first, then see the tips below!
- Heat onions. Heat butter in a large saute pan over medium heat, until melted. Add in onions and 2 tablespoons of bone broth. Saute 10-15 minutes, stirring occasionally, but not constantly.
FYI: We’re using butter for maximum flavor, but you could use olive oil if you prefer.
- Hydrate onions. Add a bit more broth, scrape any browned bits on the bottom, and continue to cook for another 10-20 minutes, until caramelized.
TIP: Time will vary depending on your stove, pan size and material, and size and shape of the onions. Reduce heat if they start to brown too much.
Troubleshooting: Why won’t my onions caramelize?
There are a few reasons that your onions might not caramelize, often with a result of burning too quickly.
So, how do you caramelize onions without burning them? Here are a few tips and mistakes to avoid:
Don’t slice the onions too thinly.
If your onions are too thin (or pieces too small), they run the risk of burning easily. Aim for slices 1/8 inch thick.
Don’t crowd the pan.
If you crowd the pan, the onions will steam and release water. This lowers the temperature and delays caramelization. They will still caramelize eventually, but take much longer.
A good rule of thumb is no more than 2 large onions in a large pan.
Avoid too high heat.
This is one of the most common issues. If you have the heat too high, your onions will burn. Go slow and steady!
You want medium heat, but may need to turn it down to medium-low if the pan heats up too much.
Make sure heat isn’t too low, either.
This is more rarely an issue, but it will take longer for your pan to reach the right temperature to caramelize if the heat is too low.
Stir occasionally, but not constantly.
Stirring too frequently can prevent your onions from caramelizing, or at least delay the process. You only need to check on them and stir every 5 minutes or so.
Don’t forget to hydrate and deglaze.
Adding a little broth to the skillet helps keep the onions hydrated, and also releases the delicious browned bits (sometimes called fond) that may stick to the bottom. Don’t add too much broth to avoid a steaming effect.
This is the most important part! Caramelized onions take time – at least 20 minutes, usually longer. It will depend on the thickness of your onions, and the size and material of your pan. It can take up to an hour if you are making a lot.
Caramelized Onion FAQs
What is the best onion for caramelized onions?
Ahhhh, this question has a few answers! While caramelized onions are typically made with yellow or white onions, you could certainly use red onion as well.
At what temperature do onions caramelize?
The chemical change to caramelize onions occurs when they reach 310 degrees F or higher – this corresponds to about medium heat on the stove.
Should you cover onions when caramelizing?
No, it’s not necessary to cover the pan. Covering would make your onions steam, which would increase the time to caramelize.
Do you salt onions when caramelizing?
It’s not necessary to add salt to this caramelized onion recipe, because we are using salted butter and bone broth. The salt actually helps bring out some of the moisture from the onions, which results in more slow, even cooking.
How can I speed up caramelizing onions?
Caramelizing onions requires patience and I don’t recommend taking shortcuts if you want the deepest caramelized flavor. However, if you really want to, you can try one of these two tricks:
- Add 1/4 teaspoon of baking soda per pound of raw onions before caramelizing. This raises the pH level, helping the Maillard reaction (i.e. caramelization!) happen faster.
- Make a smaller batch. The onions will caramelize more quickly if you have less in the pan – but you’ll also have to watch them more closely to avoid burning.
What color should caramelized onions be?
Caramelized onions should be a rich golden brown color – see the pictures in this post for reference.
Can you make this caramelized onion recipe dairy-free?
Yes, you can make the caramelized onion recipe dairy-free by using your favorite butter alternative or avocado oil. I find that the butter gives the onions great flavor, but feel free to play with it.
Can you make them ahead?
Yes, this caramelized onion recipe can be made ahead. It keeps really well and because it takes some time to make it, it’s a great component to prep ahead.
How to store quick caramelized onions
Store the onions in the refrigerator for 5-6 days.
Can caramelized onions be frozen?
Yes, you can even freeze caramelized onions! Place them in a freezer bag, push out the air, and seal. They will last 2-4 months in the freezer. Thaw in the fridge, or a bowl of warm water, before using.
How to reheat caramelized onions?
Reheat them in the microwave or in a skillet over low heat, until they sizzle.
How To Use Basic Caramelized Onions (10 Ways!)
There are many recipes with caramelized onions, and so many ways to use them! Here are the top 10 ways to use caramelized onions:
- Juicy Burgers – These onions take your burgers to the next level!
- Sirloin Steak – Homemade caramelized onions make the perfect topping for your steak.
- Pizza – Use these onions as a pizza topping on your favorite crust. My favorite low carb options are fathead pizza crust, cauliflower pizza crust, or zucchini pizza crust.
- Caramelized Onion Dip – It’s a party fave for a reason, made with just 6 ingredients and so much better than the version from the store!
- Breakfast Casserole – Stir in some caramelized onions to up the flavor! Meal prep it for busy mornings or make it for a weekend brunch.
- Smothered Pork Chops – The caramelized onion gravy on these is incredible.
- Sandwiches – Use your bread of choice! I typically use white keto bread or almond flour bread.
- Perfect Omelette – Stuff your omelettes with these onions and a touch of cheese.
- Soups & Salads – They’ll add flavor to your favorite salad or soup. Don’t forget the iconic soup that makes caramelized onions the star: French onion soup!
- Pasta – Try stirring caramelized onions into your zucchini noodles or spaghetti squash.
If you search the recipe index, I’m sure you’ll find more places to add caramelized onions for extra flavor.
What Is The Best Pan For Caramelizing Onions?
Because we want as many of the onions to be touching the pan as possible (to allow for the caramelization!), it’s best to use a large skillet. Using a skillet with high sides will help contain all of the onions before they cook down. The best pans for caramelized onions are:
- Hard anodized pan – If you want to use a nonstick pan, this kind is best for even heating. This is my personal preference.
- Cast iron pan – These hold heat exceptionally well and are particularly excellent for deglazing.
- Stainless steel pan – Another great option for even heating.
How To Make The Best Caramelized Onions
The complete guide for how to caramelize onions perfectly! This tutorial shows you the tricks and technique for the best caramelized onion recipe ever.
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Heat the butter in a large saute pan over medium heat, until melted. Add the onions and 2 tablespoons (29.57 milliliters) of broth. Saute for 10-15 minutes, stirring occasionally but not constantly.
Add 2 more tablespoons of broth to keep the onions hydrated, and scrape the bottom to deglaze. Continue to saute for 10-20 more minutes, until browned and caramelized. (Time will vary depending on your stove, pan size and material, and size and shape of the onions. Reduce heat if they start to brown too much.)
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Serving Size: 2 tablespoons
Makes 1 1/2 cups.
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Nutrition Information Per Serving
Where does nutrition info come from? Nutrition facts are provided as a courtesy, sourced from the USDA Food Database. You can find individual ingredient carb counts we use in the Low Carb & Keto Food List. Net carb count excludes fiber, erythritol, and allulose, because these do not affect blood sugar in most people. (Learn about net carbs here.) We try to be accurate, but feel free to make your own calculations.
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