Caramelized Fennel and Onions

Sliced onions and fennel, slowly cooked until lightly browned, tossed with Parmesan, lemon, and parsley.

Photography Credit: Elise Bauer

Fennel lovers, onion lovers, unite!

And then take a shower in grated Parmesan, lemon zest, and chopped parsley.

I’d like to say this is quick and easy, but it’s not quick. It’s long and easy, the sort of thing you can just put on the stove and give a stir every once in a while, as you cook the rest of the meal.

The onions and fennel are only lightly caramelized. You could cook them longer if you wanted, or sprinkle some sugar on them to bring out more of the caramelization.

But just cooking them down and lightly browning them, and then tossing them with everything else, works for me. Wonderful flavors. Terrific alongside grilled fish or chicken.

Caramelized Fennel and Onions Recipe

  • Prep time: 10 minutes
  • Cook time: 1 hour
  • Yield: Serves 4


  • 2 large onions, halved then sliced lengthwise (root to tip) in 1/4-inch thick slices
  • 2 large fennel bulbs, sliced into 1/4-inch thick slices
  • 1/4 cup olive oil
  • 1 Tbsp butter
  • Salt
  • 1/4 cup grated Parmesan
  • 2 Tbsp chopped fresh parsley
  • 1 teaspoon lemon zest
  • 2 teaspoons lemon juice


1 Cook fennel and onions in olive oil and butter: Heat olive oil and butter in a large, uncovered, wide pan on medium high heat. Add the sliced fennel and onions and stir to coat. Stir occasionally.

After about 10 minutes, sprinkle the onions and fennel with salt. Lower the temperature to medium.

You want to strike a balance between allowing the pan to get hot enough so that some caramelization (when the natural sugars in the onion and fennel start to brown) and keeping the pot from getting so hot that the onions and fennel dry out.

If it becomes an issue, you can add a couple tablespoons of water to the pan to help the onions and fennel to keep from drying out too much.

2 Scrape up browned bits: Stir occasionally, scraping up any browned bits from the bottom of the pan. Note that the browned bits are the tastiest parts.

Cook for another 30 minutes to an hour, depending on how much of a hurry you're in, and how caramelized you want your mixture to be. The longer you cook, the more caramelized and browned.

Taste test along the way to see if the cooking has been sufficient for your taste.

By the way, the onions and fennel will have plenty of flavor without having to be completely cooked down and browned all over.

3 Toss with Parmesan, parsley, lemon: When ready to serve, remove from heat and toss in the freshly grated Parmesan cheese, the chopped parsley, lemon zest and lemon juice. Taste and add more lemon juice if necessary.

Serve alone as a side to chicken or seafood, or on crackers or thinly sliced toasted baguette for a crostini. You can also use it as a filling for a rustic tart.

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How to Slice an Onion

Showing 4 of 17 Comments

  • ramona dupre'

    I love liver with onions. How do you cook the onions?

  • Amanda Delp

    What kind of pan do you use to cook this? I originally thought of a cast-iron skillet, but since you specify “pan”, I’m unsure. It sounds wonderful and very simple to make – my favorite kind of recipe. Thanks!

    Hello Amanda, I used a large, hard anodized aluminum pan to cook this, which is naturally stick-free, but you could easily use a large cast iron skillet. ~Elise

  • kwilkinson

    This recipe was wonderful. It was easy to make and it even is a great leftover! Don’t panic if the onions and fennel overflow the pan at first, just keep stirring, it will cook down. This recipe will be made again.

  • MVI

    I made this but did a vegan version as I can not eat dairy and it was absolutely fantastic. I just used Earth Balance in place of the butter and about a tablespoon of nutritional yeast in place of the cheese. The longer it cooks the more sweet it becomes. It was so good that I ate it all by itself but next time will make more and use it on pizza or with a veggie burger. Excellent and simple to make.

  • Linda Buckner

    Made this last night as a side for fresh, wild caught Copper River Salmon filet. It was a winner! I gave it the full hour plus a little more as we waited for the green beans. There was a tiny bit left over that will become crostini tonight!

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