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This caramelized onion recipe and step-by-step instruction will guide you in learn how to make caramelized onions perfectly every single time.
caramelized onions in a bowl

This caramelized onion recipe and 5-step instruction will guide you to learn how to make caramelized onions perfectly every single time.

One of the most flavorful vegetables and a staple in many cuisines are onions. Even more flavorful are caramelized onions. However, it’s also a challenging technique for many to master. That’s why we’re breaking down how to make caramelized onions perfectly every time.

caramelized onions recipe

Caramelized onions are a technique where the onion is slowly cooked in fat to trigger the release of the onion’s “natural juice” which starts the caramelization process. The result is a soft, sweet, and flavorful jam-like product.

Caramelization is a non-enzymatic reaction that happens when steam is created and the natural sugar of the onion starts to break down. Due to the high water content of an onion, it requires a longer period for the onions to sweat and to break down the sugar. Therefore caramelizing onions takes a while because it needs low heat to not burn and to have the time to properly react.

Best Way To Caramelize Onions

There are many ways to caramelize onions. Traditionally, the technique used to caramelize onions is low and slow. Alternative techniques are aimed at decreasing the time and energy to get the right consistency. However, the biggest risk with all of these methods is that it will decrease the flavor of the onions.

The First Method: High Heat & Fast

To speed up the caramelization process, this method calls for cooking on medium-high heat in butter and olive oil. To avoid having getting the onions burned you have to continuously add water and scrape the pan to deglaze. Another way is to add water in the beginning process and closing the lid to let the onions steam. The stirring starts after the water evaporates completely. At this point, the onion has reduced in size significantly.

The Second Method: Added Sugar

To help the caramelization process, you can also start by browning the onions without fat or salt. Then you add the oil and sugar to cook them until soft. This helps to get the jam-like consistency and the sweetness that characterizes caramelized onions.

The Third Method: Kitchen Appliances

Another method is using tools like an Instant Pot, Crock-Pot, slow cooker, or even an oven. These appliances allow for a more hands-off approach making the process less labor-intensive.

While all these methods may work great, what they compensate for in time they lack in flavor. In the end, nothing beats a good old-fashioned low and slow caramelization. It’s what maintains and adds the most flavor. This is also the method I will explain.

What Pan to Use?

For making caramelized onions, you want to use wide, thick-bottomed cast iron or stainless steel pan. It has to be wide to avoid overcrowding. Be careful with non-stick pans that have a special coating. Pans that have a special nonstick coating are great, but they’re so good that you won’t get any bits stuck to the bottom making deglazing redundant. Deglazing is what adds flavor to the onions, thus necessary. When using a cast iron that was just seasoned, you risk adding extra fat to the onions. Too much fat won’t let the onions caramelize properly.

Which Onions Caramelize Best?

Onions with more natural sugar will caramelize best. Masterclass.com recommends yellow onions, white onions, and Vidalia. Red onions aren’t ideal because they’re less sweet and more astringent. They’ll become more charred but still great to use as toppings, like for this Spanish Cheese & Charcuterie Board recipe.

Important Details When Caramelizing Onions

  1. Don’t overcrowd the pan with onions. Instead, add the onions in batches. Let one soften before adding the next onion.
  2. Don’t slice the onions too thick or too thin. Too thin and they can dry out and burn easily. Too thick and they will struggle to soften and caramelize.
  3. Don’t add too much fat as it will take longer to caramelize. But, less fat in the pan will result in charred onions instead of soft onions.
  4. Don’t stir too often as you want to give them a chance to brown. Stir a few times to avoid burning but give them time to brown.
  5. Watch your fire as some gas or electrical stoves don’t give consistent heat and can suddenly increase the heat.

Step-by-Step Instructions on How to Make Caramelized Onions:

Step 1: Slice the Onions

Slice the onion first lengthwise and then in half-moon slices. Create even slices of about for a consistent result.

Step 2: Add the Onions in a Heated Pan

Heat the olive oil in the pan and then add the onions in batches. To avoid overcrowding only add a new batch once the first one has softened and shrunk in size. Stir to coat them with oil.

sliced onions

Step 3: Season

Once all the onions are added, add the salt and stir. Then add the butter and stir again. According to the famous chef Roy Choi, you don’t season your onions immediately. Wait until they start breaking down to season them so they can absorb the salt and butter better.

Step 4: Cook Low and Slow

Cook the onion for about 45 minutes on low heat, stirring occasionally. Use a wooden spoon or spatula to stir. Add a splash of water to remove the bits from the bottom of the pan. Don’t stir too much but don’t let the onions burn either.

seasoned sliced onions

Step 5: Deglaze

5 minutes before the onions are done pour in red wine vinegar to deglaze the pan for the last time. Instead of red wine vinegar, you can also use red wine or dry sherry.

What To Do With Caramelized Onions?

Caramelized onions are the primary ingredient in French Onion Soup. They’re also great as toppings or can be used in dips, burgers, sandwiches, and tarts. They’re also great pairings for steaks, chicken, or fatty pork.

caramelized onions in a bowl

Perfect Caramelized Onion Recipe

This caramelized onion recipe and step-by-step instruction will guide you in learn how to make caramelized onions perfectly every single time.
5 from 1 vote
Prep Time 10 mins
Cook Time 55 mins
Course Side Dish
Cuisine American
Servings 4


Stainless steel pan


  • ¾ lb 330 gr yellow onions, peeled (about 2 large onions)
  • 1 tbsp. canola oil
  • 1 tbsp. unsalted butter
  • 1 tsp. kosher salt
  • 2 tbsp. Aceto balsamico (optional)
  • water


  • First, slice the onions in half, lengthwise. Then slice the onions evenly in thin half-moon slices. Slices of about ⅛ inch (3 mm).
  • Heat the oil in a pan over low heat and add the onions gradually without overcrowding the pan. Add them in small batches, if necessary, by letting one batch soften first before adding the next one. Stir to coat them in oil.
  • Once all the onions are softened, season them with salt and add the butter. Stir again. Cook the onions on low heat. Stir only when necessary using a wooden spatula to prevent the onions from burning. Add a splash of water to scrape down the pieces stuck on the pan. Keep cooking the onions and scraping the pan for about 45 minutes until the onions are deep golden brown. Just before the onions are done add in the balsamic vinegar to deglaze the pan for the last time by scraping down the bottom of the pan. To make dip or toppings, cook the onions for about 10 minutes or more until they get a darker shade of brown.


Using balsamic vinegar and butter is optional but adds flavor to your onions.
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