How to Caramelize Onions

Think Low and Slow With This Step-by-Step Guide

Caramelized Onions
The Spruce / Elaine Lemm
  • 01 of 07

    Gather the Ingredients.

    Caramelized Onions Ingredients
    The Spruce / Elaine Lemm

    Caramelized onions are not synonymous with grilled onions. Both have their place and grilled onions can be delicious, but grilling is about high heat and caramelization happens slowly over low heat.

    Caramelization is a chemical change that makes carbohydrates (e.g. sugars) turn brown when heated to temperatures of 310 F or higher. The best onions for caramelizing are the so-called "sweet" onion varieties:

    • Vidalia (Georgia)
    • Walla Walla (Washington)
    • Sweet Imperial (California)
    • Oso Sweet (Chile)
    • Texas Sweet (Texas)
    • Mayan Sweet (Mexico)
    • Maui (Hawaii)
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  • 02 of 07

    Heat Oil in a Nonstick Pan

    Caramelized Onions Butter and Oil in pan
    The Spruce / Elaine Lemm

    Let the oil get hot for a moment. A general rule of thumb is to use 2 tablespoons of oil for every three onions. If you like, you can use a mixture of oil and butter. Clarified butter is best, since it won't burn as easily as ordinary butter. As long as you don't let things get too hot, your butter won't burn.

    As long as we keep things at 310 to 320 F, you can use practically any oil, even olive oil, which has a very low smoke point. But since it's hard to know the exact temperature, stick with butter or a combination of butter and vegetable oil. Coconut oil will work, too.

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  • 03 of 07

    Add the Sliced Onions

    sliced onions on pot
    The Spruce / Elaine Lemm

    Keep the onions moving around the pan so they don't burn. They'll cook down quite a bit in volume, so it's normal if the pan seems too full at the beginning.

    Continue to 4 of 7 below.
  • 04 of 07

    Let the Onions Turn Translucent

    Sliced onions in pan cooked translucent
    The Spruce / Elaine Lemm

    As you cook them, the onions will start to soften and turn translucent. The reason sweet onions are used is that they have a higher sugar content and it's the sugar that's actually turning brown. Ordinary yellow onions have some–but not as much–sugar in them and you can certainly caramelize them as well.

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  • 05 of 07

    Allow the Onions to Soften

    Browned onion slices
    The Spruce / Elaine Lemm

    By this time the onions will have softened and cooked down to a fraction of their previous size, as the water in them has slowly cooked away. They'll also have a slightly sticky consistency. That's because of the sugars being released in the onions.

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  • 06 of 07

    Develop the Golden-Brown Color

    Caramelized Onions Browning
    The Spruce / Elaine Lemm

    See the golden brown color beginning to develop? You're well on your way to caramelized onion.

    Continue to 7 of 7 below.
  • 07 of 07

    The Caramelized Onions

    Caramelized Onions Finished
    The Spruce / Elaine Lemm

    Here they are—a rich, golden brown hue and bursting with smoky, sweet onion flavor. Need an excuse to throw a few burgers on the grill? Delicious caramelized onions like this are all the reason you need. Also, try this classic French onion soup

    Here's an appetizer idea as well: get some puff pastry and spread a sheet of it on a baking pan. Brush it with butter, then top it with caramelized onions and chunks of Brie and bake until the cheese is melted and the pastry is puffy and golden brown.