How long do caramelized onions keep? How should I store them?

Caramelized onions will keep in a covered container in the fridge for up to 2 weeks, or they can be frozen for up to 3 months. If freezing, you can divide them into small containers or freezer bags to thaw and use as needed.

What type of onion is best for caramelizing?

While you can caramelize any type of onion, yellow onions are ideal for their balance of sweet and savory flavors. Sweet onions, like Vidalia or Walla Walla, can also be used and will result in a slightly sweeter finished product. Feel free to use a mix for a more nuanced taste.

Caramelized Onions - Once Upon a Chef

Caramelized Onions

By Jenn Segal

Jammy, sweet caramelized onions can transform the simplest dishes, like grilled cheese and burgers, into cheffy delights.

Servings: 1½ cups

Prep Time: 15 Minutes

Cook Time: 1 Hour

Total Time: 1 Hour 15 Minutes

Ingredients

4 tablespoons unsalted butter
1 tablespoon vegetable oil
3 pounds yellow or Vidalia onions (or a combination), halved and thinly sliced
¾ teaspoon salt
½ teaspoon freshly ground black pepper
¾ teaspoon sugar
About 1 cup water, as needed

Instructions

In a large, heavy-bottomed skillet, melt the butter with the oil over medium-high heat. Add the onions, salt, pepper, and sugar. Cook, uncovered, stirring frequently with a wooden spoon, until the onions are slightly softened, 4 to 5 minutes.
Reduce the heat to medium and continue cooking, uncovered and stirring occasionally, until the onions are a rich golden brown color. This process can take anywhere from 45 to 75 minutes. In the beginning, you will only need to stir the onions occasionally. However, as the onions cook down and begin to brown, you will need to stir them more frequently, scraping the fond (the brown particles) from the bottom of the pan. Towards the end of the caramelization process, the fond will start to stick to the pan, so you will need to occasionally deglaze the pan with a few tablespoons of water, scraping up the fond with a wooden spoon, to prevent burning and promote even caramelization. Repeat the deglazing process with the water as needed until caramelization is achieved. Once the onions have achieved the rich golden brown color, remove them from the skillet, let cool, and store in a covered container in the refrigerator.
Make-Ahead/Freezing Instructions: The onions will keep in a covered container in the fridge for up to 2 weeks, or they can be frozen for up to 3 months. If freezing, you can divide them into small containers or freezer bags to thaw and use as needed.

Nutrition Information

Per serving (8 servings)
Serving size: 3 tablespoons
Calories: 123
Fat: 8 g
Saturated fat: 4 g
Carbohydrates: 13 g
Sugar: 9 g
Fiber: 2 g
Protein: 1 g
Sodium: 233 mg
Cholesterol: 15 mg

Gluten-Free Adaptable Note

To the best of my knowledge, all of the ingredients used in this recipe are gluten-free or widely available in gluten-free versions. There is hidden gluten in many foods; if you're following a gluten-free diet or cooking for someone with gluten allergies, always read the labels of your ingredients to verify that they are gluten-free.