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How to caramelize onions.
4.84 from 18 votes

How to Caramelize Onions

Caramelized onions are made by cooking onions low and slow until golden, delicious, and intensely flavorful and learning how to properly caramelize onions is key. Learn how with this easy step-by-step tutorial.
Prep Time10 mins
Cook Time50 mins
Total Time1 hr
Servings: 2 cups (approx)
Calories: 274kcal

Ingredients

  • 5 large onions - yellow, white, or red
  • 2 tablespoon olive oil
  • 1 tablespoon butter - (optional)
  • salt
  • balsamic vinegar - (optional)

Instructions

  • Prepare the onions: Use a sturdy knife to slice approximately 1/2-inch off each stem end and roots off the root end. Cut each onion in half, stem to root, and peel. Lay the onions cut-side-down and cut, again from stem to root, into slices approximately 1/4 to 1/2-inch thick. Repeat with all onions.
  • Start cooking the onions: Set a large, heavy-bottomed sauté pan or skillet over medium heat. Add the olive oil and butter (if using) and swirl to coat the bottom of your pan. Heat the oil until shimmering and hot, then add the onions. Mix well to coat the onions in oil.
  • Continue to cook your onions: Allow your onions to cook, stirring occasionally. If you start to see your onions browning, reduce heat to medium-low (remember: we're cooking these onions low and slow). After approximately 10 minutes, sprinkle with salt (approximately 1/2 teaspoon) and stir to combine. By this point, your onions should be softening and lightly golden. If your onions start to dry out and brown/burn prematurely, as a result, (assuming your heat is set to medium-low), add a few teaspoons of water to the pan.
  • Continue to cook, stirring often: Continue to cook your onions for an additional 30-45 minutes, stirring every 2-3 minutes to prevent burning. You don't want to stir continuously, but just often enough that the onions have enough time to cook and stick to the bottom of your skillet, browning just slightly - but not burning. If you stir too often, they won't brown. If you don't stir often enough, they will burn. I like to keep my stove set to medium-low and cook my onions for at least 50-60 minutes.
  • Use a metal spatula to scrape your pan often: After the first 30 minutes, you'll find that your onions are nice a deeply rich golden color. Every minute or so, use a metal spatula to scrape up the brown bits from the bottom of your skillet. Continue to cook, stir, and scrape the brown bits from the bottom of the pan until your onions are a rich golden brown color.
  • Serve or store: Remove from heat and serve with all your favorite recipes or transfer to a sealed container and keep stored in the refrigerator for up to 4 days.

Notes

  • Variations: At the end of cooking deglaze your pan with a splash of balsamic vinegar or red wine. This is completely optional, but it adds a delicious, complex flavor to your onions (highly recommended when adding your onions to pizza or pasta).
  • Turning up the heat won't caramelize your onions faster. Don't rush it.
  • You may use any type of onion, but yellow onions, sweet onions, red onions, or white onions are best.
  • How to prevent fond (sticky brown bits) from burning? Make sure the heat is set to medium-low or low and use a metal spatula to scrape the bottom of your pan every 1-2 minutes. You can also deglaze your pan with a bit of water.
  • Some people add a teaspoon of regular or brown sugar at the same time that the salt is added (approx 10 minutes into cooking). I find this unnecessary.
  • Storage: Keep stored in the refrigerator for up to one week or freeze in sealed ziplock bags for up to 3 months.
  • Caramelized onions are naturally gluten-free and vegetarian. To make this recipe vegan, omit the butter.
Originally published December 23, 2019

Nutrition

Calories: 274kcal | Carbohydrates: 35g | Protein: 4g | Fat: 14g | Saturated Fat: 2g | Sodium: 15mg | Potassium: 548mg | Fiber: 6g | Sugar: 16g | Vitamin C: 28mg | Calcium: 86mg | Iron: 1mg
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