Friday, August 21, 2009

Recipe: Caramelized Onions

Onions caramelized in a cast iron skillet

Cast iron's highest and best use may well be to caramelize onions. You get even heat, near-perfect blackbody radiation, a nonstick surface, good looks, charming personality, the list goes on...

Caramelized onions are a mainstay of proper fajitas; as well as a strong supporting cast member in many other tasty dishes like quesadillas, pizza, breakfast potatoes, tacos, enchiladas, and marinara sauce.

I like to include butter when I caramelize onions, as the browning of the butter helps add a nice nutty flavor. There's also salt in butter, which combines with the sweetness of the onions to further develop the flavor.

Here's how to make perfect caramelized onions in your cast iron skillet:

  • sliced onions (6 large yellow onions are pictured here)
  • oil (About 2 tablespoons are used here)
  • butter (about 1/4 stick is used here, use more oil if you're leaving the butter out.)

Onions being properly sliced
Slice the onions by cutting off the tops and bottoms. Then, cut the onions in half from what was formerly the top to the bottom, making two semi-spherical halves.

Remove the outer skin layers. Place each onion half flat side down on your cutting board. Slice the onions evenly at about 1/8 inch thickness—from one "pole" to the other.

This produces even, crescent-shaped pieces of onion that are easy to manage on the fork (see picture at right).

To begin caramelizing the onions, heat a medium cast iron skillet on medium heat until hot (just barely starting to smoke).

Add the oil and toss in the sliced onions. Stir the onions around the skillet every 4 minutes or so, gradually lowering the heat by a few ticks with each stirring to end up around medium low heat after about 15 minutes.

If you are including butter, toss in about 1/4 stick somewhere near the 10-minute mark. Turn off the heat when the onions are a deep golden brown. This will take about 20 minutes.

Serve caramelized onions right away, if appropriate according to your dinner or lunch plan.

Caramelized onions are resilient... so feel free to leave them on the stove in the cast iron skillet (covered, no heat) for up to 4 hours, and simply re-heat for 5-10 minutes on medium heat to serve with the rest of the meal when everything is ready.


  1. Thanks for posting! I never had been able to carmelize onions until I read your post recently.

  2. Hey Alicia,

    So glad you found it helpful. Thanks for posting!


  3. They don't look very carmelly to me.

  4. Hi Christine,

    Sorry that the pictures don't do them justice... however I can assure you that they are caramel-ey, sweet, and delicious. Please let me know if you find otherwise after trying the recipe.




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