Balsamic Caramelized Onions | The Best Caramelized Onions Recipe (2024)

FAQs

What is the secret to caramelize onions? ›

While you can start the cooking process at medium heat, low and slow is the name of the game when it comes to caramelizing onions. Once your onions begin to soften and take on a golden hue, you'll want to reduce the heat from medium to medium-low or even low for the remainder of the cooking process.

You can caramelize any kind of onion, but yellow or Spanish onions tend to offer the most balanced-sweet-savory flavor profile and are the most versatile for different dishes. Sweet onions, such as Vidalia or Walla Walla work too, but keep in mind that their flavor will become even sweeter once caramelized.

Our Test Kitchen likes to use butter when caramelizing onions, as it offers the richest flavor. If you avoid dairy or don't have butter, you can caramelize onions in other fat such as margarine or olive oil. Add the onion slices. It's okay if they overlap a bit here because they'll shrink as they cook down.

Tip: use apple cider vinegar for white and yellow onions and balsamic vinegar for red onions. Tip: the vinegar serves to deglaze the pan, adds acidity, and brings this recipe together by boosting the tangy and savory flavors of the caramelized onions. If the onions stick to the pan, that's fine.

The first phase of the process is softening the onions so that they collapse into a tender mass while releasing a good deal of their liquid. If you cover the pan, you'll trap steam, which will speed up their softening, heat them more quickly, and help release their liquid more quickly.

So using baking soda will speed up the process. But you have to be careful. If you add too much, it will impact the flavor. Different recipes recommend anywhere from ⅛ to ¼ teaspoon per pound of onions (aka about 3 large onions).

It's not necessary, but it will add some additional flavor.

If the onions aren't deeply brown after 50 minutes and you'd like to speed things up, you can turn the heat higher to get more caramelization. Stir continuously to prevent burning.

Fold onions with a spatula, scraping bottom of pan to ensure they don't stick or scorch. Cook, stirring every 5 to 6 minutes and reducing heat as necessary to maintain a gentle simmer, until liquid has evaporated, about 35 minutes.

You definitely want the flavor of butter in your onions—but butter has the tendency to burn. For insurance, use a combination of butter and oil, which has a higher smoking point. But how much do you use? Depending on the consistency you want your onions, you can use more or less fat.

Do you caramelize onions on low or high heat? ›

The key to making Caramelized Onions is cooking them low and slow. No more than medium heat and plan for it to take awhile.

Why are my caramelized onions bitter? It's likely you are cooking them too fast/on too high a heat, which results in burned, not caramalized, onions. The trick to caramelizing onions is low heat and slow cooking. It can take a while, especially if you start with a big batch.

When you add baking soda during cooking it changes the pH which increases the Maillard reaction causing the onions to brown more quickly. The higher pH also causes the onions to soften more quickly, which we cover below when we discuss the texture.

Squeeze some lemon juice or vinegar into the dish. The acidity helps to neutralize the onion flavor.

The baking soda speeds up the Maillard reaction

According to cookbook author and food writer Kenji López-Alt, you can speed up the process of caramelizing onions by adding a pinch of baking soda (via Serious Eats).

Unlike mushrooms, which shouldn't be salted until after they've browned, you should always salt onions before you start cooking them. Onions won't begin to caramelize until all the water in them has evaporated, and using salt will speed up that process, Caicedo explains.

Cranking up the heat too high.

Caramelizing onions is not an instant gratification process; they take a while to cook. It may be tempting to crank up the heat to speed the process along, but that's the worst thing you can do; it only puts you more at risk for burning your onions.