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.

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.

After 10 minutes, sprinkle some salt over the onions, and if you want, you can add some sugar to help with the caramelization process. (I add only about a teaspoon of sugar for 5 onions, you can add more.) One trick to keeping the onions from drying out as they cook is to add a little water to the pan.

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.

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.

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).

If you need to caramelize onions quickly, adding sugar or a pinch of baking soda (to raise the pH level and help them brown quicker) can help to speed up the caramelization process but truly they aren't a dish that cooks up quickly. If using baking soda I'd suggest about 1/4 tsp per pound of raw onions.

Yes, you should cover the onions when caramelizing them. Covering the onions helps to trap the steam and heat, which aids in the caramelization process by softening the onions and allowing them to release their natural sugars. This results in a sweet and flavorful caramelized onion.

Thinly sliced onions will burn faster and stick to the bottom of your pan. Aim to slice your onions 1/8" thick—their heft will prevent them from drying out. You definitely want the flavor of butter in your onions—but butter has the tendency to burn.

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.

Why did my caramelized onions turn to mush? ›

Using baking soda to caramelize onions

Stir it in at the end of cooking for about 1 minute. Adding it too early will break down the onion fibers, turning them into mush.

Stainless steel or cast iron skillets are ideal for caramelizing onions.

You don't need the balsamic vinegar, which is only there to add some flavour. The caramelization — the browning of the sugar in the onions — will take place just fine without the vinegar. Absolutely! You only need oil or butter or a bit of each in a frying pan.

You don't want to slice them too thin or they'll cook too fast which could cause them to burn. You'll also want to start out with fat. I choose oil and butter. Butter gives it a good flavor and helps with the caramelization and the oil helps the butter not to brown too fast.

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.

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.

Instructions. Heat the oil in a large skillet over medium-high heat. Add the onions, peppers, salt and pepper. Reduce the heat to medium-low and cook, stirring frequently, until the onions are caramelized and the peppers are tender and slightly browned, 15 to 20 minutes.