How to Caramelize Onions for Burgers

Learn how to caramelize onions easily on your stove in a cast iron skillet. With only two basic ingredients, create these delicious, melt-in-your-mouth onions that add incredible flavor to a beef burger.

caramelized onions in a cast iron skillet

Carmelized onions bring sweetness to various dishes, making their taste stand out. The browned onions offer a tender bite with a hint of crunch.

The onion caramelization process is so easy! With only two simple ingredients, you will focus on the onions’ natural sweetness. There is no need to add brown sugar, balsamic vinegar, or Worcestershire sauce.

Using basic pantry ingredients, onions, and butter, you will create the best caramelized onions that are pure, delicious, and easy to make!

caramelized onions on homemade burgers

Ingredients for Caramelized Onions

To make caramelized onion, you will need:

  • Onions – You can use white, yellow, or red onions for caramelizing. I like to use white onions as they have a stronger flavor.
  • Butter – Instead of using oil, use butter for the best flavor.

For kitchen essentials, you will need a knife, wooden spoon, a cutting board, and a large cast iron skillet.

How to Caramelize Onions for Burgers

To caramelize onions for burgers:

  • Slice the Onions – Start by peeling a minimum of two onions. Keep in mind that raw onions shrink during caramelization. When preparing onions for burgers, I like to slice them into rings.
  • Heat Butter – Melt butter in a large cast-iron skillet over medium-low heat.
  • Add Onions – Add the sliced onions to the hot skillet. Toss them to coat with the butter. Allow them to simmer for 10-15 minutes.
  • Caramelize – Cook the onions slowly, stirring occasionally. This process can take around 20 to 30 minutes. The exact timing will vary depending on how thick the onions are sliced. Keep the heat low to prevent burning.
  • Serve – Once deep golden brown, the cooked onions are ready to be placed on your burger patty to add flavor and sweetness.

Recipe Tips

  • Slice Evenly – Cut the onions into even-sized thin slices. This ensures even cooking and caramelization.
  • Avoid Overcrowding – Onions will shrink as they are caramelizing but you want to use a large skillet with enough surface area to spread them out. This will help them cook evenly.
  • Butter – For the best flavor, use butter and avoid using olive oil.

How to Store

  • Room Temperature – Caramelized onions can be kept at room temperature for up to two hours while serving.
  • Refrigerate – Place the onions in an airtight container once they are cooked and cooled to room temperature. You can use a glass or plastic container and store it in the fridge for up to one week.
  • Freeze – Place portions in airtight freezer-safe bags or containers. They can be frozen for three months.
  • Reheat – To reheat the onions, place them in a skillet over low heat until hot.

Recipe FAQs

Caramelized onions on burger

What to Serve With Caramelized Onions

  1. Cast iron skillet burgers are juicy and savory, creating a delicious way to serve caramelized onions.
  2. Crispy and golden, these homemade french fries provide the perfect side for juicy burgers and onions.

Caramelized Onion Recipe Card

caramelized onions in a cast iron skillet

How to Caramelize Onions for Burgers

Yield: 8
Prep Time: 5 minutes
Cook Time: 25 minutes
Total Time: 30 minutes

Learn how to caramelize onions easily on your stove in a cast iron skillet. With only two basic ingredients, create these delicious, melt-in-your-mouth onions that add incredible flavor to burgers, sliders, and steaks.

Ingredients

  • 2 large onions
  • 3 tablespoons butter

Instructions

  1. Slice the Onions – Start by peeling a minimum of two onions. Keep in mind that raw onions shrink during caramelization. When preparing onions for burgers, I like to slice them into rings.
  2. Heat Butter – Melt the butter in a large cast iron skillet over medium-low heat.
  3. Add Onions – Add the sliced onions to the skillet. Toss them to coat with the butter. Allow them to simmer for 10-15 minutes.
  4. Caramelize – Cook the onions slowly, stirring occasionally. This process can take around 20 minutes. Keep the heat low to prevent burning.
  5. Serve – Once the onions are deep golden brown, they are ready to be placed on your burgers to add flavor and sweetness.

Notes

  • Reheat – To reheat the onions, place them in a skillet over low heat until hot.
  • Slice Evenly – Slice the onions evenly. This ensures even cooking and caramelization.
  • Avoid Overcrowding – Onions will shrink as they are caramelizing but you want to use a large skillet with enough surface area to spread them out. This will help them cook evenly.
  • How To Store

    • Room Temperature – Caramelized onions can be kept at room temperature for up to two hours while serving.
    • Refrigerate – Place the onions in an airtight container once they are cooked and cooled to room temperature. You can use a glass or plastic container and store it in the fridge for up to one week.
    • Freeze – Place portions in airtight freezer-safe bags or containers. They can be frozen for three months.

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    About the Author
    Sarah is the author behind Rocky Hedge Farm. With a passion for simple, healthy recipes, gardening, and remodeling her manufactured home, she shares her experiences and knowledge to inspire others. Go here to read her story, “Living a Life of Contentment and Joy: Simple Living at Rocky Hedge Farm.” If you want to message Sarah, visit her contact page here.

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