Caramelized Onions

Article by Layla Khoury-Hanold and Andy Liang

Onions are an everyday, flavor foundation-building ingredient that need heat and time to transform their taste from sharp to mellow. But when you take the extra time to caramelize them, the humble onion is transformed into a sweet, flavor-enhancing powerhouse. The chefs in the Food Network test kitchen made more than 10 batches of caramelized onions, testing different methods side-by-side to bring you the very best version of caramelized onions that exists.

How Long Does It Take to Caramelize Onions?

It takes about 45 minutes to make true, deeply caramelized onions in a stainless-steel skillet. Online, some recipes call for sugar or baking soda to speed up the process, but we found that sugar makes the onion too sweet and baking soda leaves a metallic taste. The only “hack” that doesn’t affect the final product but does cut down on time is steaming the onions with a touch of water until wilted, so more onion surface touches the bottom of the pan and browns evenly. We incorporated this technique into the recipe.

The Best Onions for Caramelized Onions

Classically, caramelized onions are made from yellow onions, also known as Spanish onions. This is what we reached for in our testing. However, you can caramelize any type of onion including shallots or even a combination of different onions you have on hand.

The Best Pan for Caramelized Onions

We’ve seen recipes call for all sorts of skillets for caramelized onions, from stainless-steel to nonstick skillets to Dutch ovens. We decided stainless steel skillets are the best option. Stainless-steel heats evenly, caramelizing the onions well without burning them in places. You could also use a Dutch oven, but the process will take longer.

How to Cut Onions for Caramelized Onions

There are two different ways to slice an onion: pole to pole, or crosswise (the way you’d slice an onion for a burger topping).

• Pole to pole (pictured above): Halve an onion, peel it, then slice it on an angle between the tip and stem end: this is cutting pole to pole. While doing so, you cut along the “grain” of the onion. When we caramelized onions cut pole to pole, they softened beautifully yet kept their shape. We highly recommend slicing the onions this way for caramelized onions.

• Crosswise: When we cut onions crosswise into half-moons, the caramelized onions had a soft, mashed texture ideal for something like a bacon onion jam.That’s because cutting crosswise cuts through the cell walls of an onion, breaking down the structures which hold their shape.

Should You Caramelize Onions In Butter or Olive Oil?

We tested both cooking oils in our quest to develop the perfect caramelized onions recipe. Here’s what we found.

• Butter: Butter highlighted the caramel flavor of the onions, making for intoxicatingly rich results. We preferred the butter; if you can use it, we highly recommend doing so.

• Olive oil: This oil browned the onion more quickly than butter did, because butter contains more water than olive oil (and therefore cooks ingredients more slowly). It made for tasty caramelized onions with a clean taste and can be used in a pinch or to accommodate dietary restrictions.

What to Know about Deglazing the Pan

While you’re slowly cooking the onion, it will caramelize a bit onto the pan into brown patchy areas. As this happens, you can pour a small amount of liquid (about 1 tablespoon) into the pan, which will quickly remove the caramelization from the pan and transfer it to the onions. Traditionally, caramelized onion recipes don’t deglaze these browned bits, but this runs the risk of burning. Therefore, we decided that deglazing was a smart, low-lift step.

We set to work testing different de-glazing liquids:

• Beef stock: We tried deglazing with this because it’s classically used in French-onion soup. It ended up being our favorite option: paired with the richness of butter, it amplified the sweet onion and added layers of savory umami, too, due to the beef stock reducing and concentrating in flavor.

• Water: This is the most popular deglazing ingredient used in other online recipes. It delivered perfectly delightful caramelized onions. We think it’s a good swap to use for beef stock, if you don’t have it on hand.

• White wine: We briefly considered testing red wine, too. Ultimately, we didn’t, because we didn’t want a strong red wine flavor or red color in our caramelized onions. Instead, we reached for a dry pinot grigio for the test. The results ended up being tangy and tannic: delightful, but not the classic sweet-savory caramelized onions flavor we sought.

How to Use Caramelized Onions

There are many different ways to use caramelized onions, but here are a few of our favorite:

• In French Onion Soup: Tyler Florence’s French Onion Soup is a classic.

• As a burger topping: See Ina Garten’s Smashed Hamburgers with Caramelized Onions.

• Stirred into a quiche: Ellie Krieger’s Caramelized Onion, Mushroom and Gruyere Quiche with Oat Crust is light but satisfying.

• Folded into pasta: Food Network Kitchen’s Pasta with Caramelized Onions and Mushrooms is a great place to start.

How to Store and Reheat Caramelized Onions

Store cooled caramelized onions in the fridge in an airtight container for up to four days. Reheat them in the microwave or in a nonstick skillet over medium-low heat, stirring frequently.

Can You Freeze Caramelized Onions?

Caramelized onions freeze beautifully, all the more reason to make a big batch while you’re taking the time. Once the caramelized onions have cooled, scoop tablespoon-fulls onto a parchment paper-lined baking sheet, freeze for an hour, then transfer the frozen portions to a resealable freezer-safe bag or air-tight container. Or make portions by filling an ice cube tray and freezing, then transfer to a freezer-safe bag or container. This way, you can thaw just what you need, whether it’s a bag-full for a jammy onion pasta sauce or just a dollop for a sandwich topping. Caramelized onions will keep for up to 3 months in the freezer.