Two simple ingredients transform into something delicious & beautiful when you learn how to caramelize onions. When cooked slowly over low heat, sliced onions turn golden brown, tender, sweet, & buttery. Before you know it, you will be adding these golden sweet strings of onion to everything.
It takes a bit of time and patience, but there is no better recipe for onion lovers. Making homemade caramelized onions is so easy to do, you will be wondering why it took you so long to start making them.
Sweet flavorful caramelized onion adds so much flavor to even the most simple of dishes. For instance, this is what makes French onion soup so amazing. They are the star of my 3-Cheese Mac & Cheese. I highly recommend mastering the art of caramelizing onions to up the flavor profile in your home cooking.
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Best Onions for Caramelizing
You can use either white or yellow onions for caramelizing. I like to use a white onion for a balance between the spicy pungent flavor of it with the added sweetness as it cooks. For balanced flavor, the best onions to caramelize are white or yellow varieties.
A sweet onion will only get sweeter while you cook it. So if you want an intense sugary flavor, start with a sweet yellow onion like Vidalia, Maui, or Walla Walla. Red onions can also be used to caramelize. Almost any variety of onions will work, except shallots & green onions.
Ingredients
It takes only two ingredients to make amazing homemade caramelized onions. This recipe is made without sugar or balsamic vinegar like other recipes. Just butter and onions in this classic method.
I prefer to use butter instead of oil when cooking onions. Salted butter is my go-to. If you want a low-sodium version, use unsalted butter.
- Salted Butter
- Yellow or White Onion
- additional salt - optional
See the recipe card for quantities.
Instructions
Here are the easy step-by-step instructions for this caramelized onion recipe. I have included photos at different time intervals and stages so you can see how the recipe progresses as it cooks. The raw onions will cook slowly to become soft, translucent, then golden, and finally brown. These are the beautiful stages of cooked onions.
Begin by using a heavy pot that will cook evenly. I recommend using a pot that is sized large enough to cook the sliced onions so they are not piled too high. Try and cook them so they are layered only about 2-3 on top of each other. They will eventually cook down to a single layer and that is perfect. Do not overcrowd the pot or pan.
Slice the onions to a medium thickness. Using a mandoline to get uniform slices is recommended. If they are too thin they will cook too fast and burn before they reach ideal sweetness levels. If they are too thick, they will take a long time to cook. Aim for slices about as thick as shown below.
Caramelize Onions on the Stovetop
Making caramelized onions take minimal effort and the occasional stir. Since they are done at such low heat, they do not need constant attention or babysitting. This is what is so great about them. You can go about cooking or doing other things while the magic happens.
Add the butter to a medium-sized pot. Melt the butter on low heat. On my stove I have it set on 3.
Once the butter has melted, add the sliced onions to the pot.
Cook on low heat, stir occasionally. This is what it looks like after 5 minutes.
Continue to stir the onions and cook over low heat. This is what it looks like after 15 minutes.
After 30 minutes of cooking onions low and slow, they will start to caramelize. The sliced onions will be soft and translucent. While stirring scrap up the tiny bits that may stick to the bottom. Those flavor bits are so good. Some of them will start to brown and turn golden, as seen below.
Hint: Once they start browning, do not get impatient. Do not try and speed up the process by turning up the heat. Continue to cook them on low while stirring. It will be another 15-30 minutes until the caramelizing is done. Total time is between 45-60 minutes.
Top tips
- Cut the onions evenly to a medium thickness
- Do not overcrowd the pan
- Only cook over a low heat
- Stir occasionally
- Enjoy them on just about anything
How to Tell Caramelized Onions are Done
Onions will be caramelized and ready to eat once they are golden to dark brown. They will reach a sweet & creamy texture as soon as they are they have light brown edges with some still white. They will smell sweet versus pungent and be so tender they may start to fall apart.
At this point, the caramelized onions can be done. I like to cook them to a light brown or blonde color when I am using them in recipes where they will cook further - like in casseroles or soups. If they will be a topping on something, cook the onions until a medium brown or amber color.
However, you can take them even further. Caramelized onions may be cooked for even longer if you want a richer deep flavor. For medium to dark brown caramelization, continue to cook the onions over low heat for another 30 minutes for a total of 90 minutes.
This is how it looked for me after 45 minutes.
How Long Does it Take to Caramelize Onions?
Most people wonder why it takes so long for onions to caramelize. When I first made them, I thought the same thing. I had been stirring and watching for what seemed like forever. But in the end, it was way worth the patience and wait.
It takes a long time for onions to caramelize because it takes time for the moisture to release from the onions. When you caramelize onions you are not simply browning or sauteeing them. The slow process takes typically between 45-60 minutes, depending on how many onions are caramelized.
The caramelize them correctly, the best way to cook them is over low heat to "sweat" out the moisture slowly. Once all the moisture is released, the soft almost translucent onion strings will then release the natural sugars. Those sugars, not high heat, are what brown the onions and cause them to have that beautiful color and silky texture.
Recipes Using Caramelized Onions
Not that you have a pile of yummy freshly made caramelized onions, let's use them in some amazing recipes. My favorite way to use them is as a topping for steaks or grilled chicken thighs. They are great also in sandwiches like my Easy 3-Ingredient Sloppy Joes. Here are some of the best things to eat with caramelized onions.
- Sandwiches - add to patty melts, hamburgers, hot dogs/sausages, grilled cheese, hoagies & homemade Philly cheesesteaks.
- Pastas - add to mac & cheese, baked rigatoni, spaghetti sauce, or cold pasta salads.
- Topping for everything! - use as a topping on baked potatoes, creamed soups, green salads, pizzas, flatbreads, dips, frittatas, tacos, nachos, & roast beef sliders.
Equipment
To caramelize onions evenly, I recommend a quality pot, skillet, or saute pan. You want to use one with a thick bottom that will distribute heat evenly but not overheat. I find cast iron retains heat at too high a level and don't recommend cooking in one for this recipe.
Using a mandoline for even slices is helpful too. Here are my recommendations for the best kitchen tools to make caramelized onions.
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Storing Caramelized Onions
Leftover caramelized onions store very well. They are a great make-ahead recipe that keeps for days. I recommend making a big batch so you have plenty to add to just about anything and everything.
Place caramelized onions in an airtight container and store them in the refrigerator for up to 5 days. You can also freeze them. Store in an airtight container and place in the freezer for up to 3 months.
You can also portion caramelized onions out and put spoonfuls in an ice tray. Freeze until solid and then pop them out into a Ziploc. Defrost a small amount at a time and use it later. Add them to burgers, sandwiches, pasta, & just about any recipe to make it even better.
FAQ
I prefer the flavor that butter brings to rich sweet slow-cooked onions. When caramelizing them it is done over low heat so worrying about the smoke point is not needed. Therefore, you don't need to use oil for fear of the butter burning or browning.
Oil can be used in place of butter when caramelizing onions. A combination of both oil and butter is a wonderful way option. If you want to use oil I recommend olive oil or avocado oil as the best choices for caramelizing onions.
You may have heard that adding sugar helps caramelize onions faster. If you want very sweet onions with a sugar coating to help brown that, this may be the trick you are looking for.
However, the point of caramelizing onions is to brown them slowly so the natural sweetness builds and comes out. The flavor of these two simple ingredients, butter & onion, is all you need. For this reason, I do not recommend using sugar during the caramelization process.
The slow process of caramelizing onions is not best done with small diced pieces. Medium slices work best and are my recommendation.
How to Caramelize Onions
Ingredients
- 1 medium-sized onion
- 2 tablespoons salted butter
Instructions
- Slice the onions to a medium thickness. Using a mandoline to get uniform slices is recommended.
- Add the butter to a medium-sized pot. Melt the butter on low heat.
- Once the butter has melted, add the sliced onions to the pot.
- Cook on low heat, stir occasionally.
- After 30 minutes of cooking onions low and slow, they will start to caramelize. The sliced onions will be soft and translucent. Some of them will start to brown and turn golden,
- Continue cooking for another 15-30 minutes depending on how dark and rich you want your caramelized onions.
- Total cook time should be between 45-60 minutes. Once done, turn the stove off.
- Use the caramelized onions in a recipe or add them to a burger, sandwich, or omelet. This makes about 8 servings if added to a recipe. Depending on the size of your onion, you will have approximately ½ cup of caramelized onions.
- Store leftovers in the refrigerator or freezer.
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