Ultimate Flank Steak Sandwich With Caramelized Onions and Cream Cheese on Ciabatta

I had some leftover flank steak sitting in the fridge and decided to use it to make the World’s Best Flank Steak Sandwich!  This sandwich was an absolute beast and didn’t require a lot of extra effort.

We are talking about a sandwich on a toasted ciabatta roll that has:

  • Tender Flank Steak
  • Caramelized Onions
  • Jalapeno Cream Cheese
  • Steak Sauce

How could this not be amazing?

Flank Steak Sandwich with Onions and Cream Cheese

Start by Caramelizing the Onions

I started with a large Vidalia onion, removed the peel, and sliced it thinly.

Heat a cast iron skillet over Medium heat then add a tablespoon of butter, the sliced onions and a pinch of salt.

Let the onions cook down and give them a stir every few minutes.  After about 10 minutes throw in a quarter cup of water to steam the onions and deglaze the skillet a little.  Cook until the water has evaporated and the onions are soft, tender and browned.  The who process will take about 15-20 minutes.

Sliced Onions in Cast Iron Pan

Assemble the Sandwich Ingredients

I was using thin slices of the Costco flank steak I cooked in an air fryer that were a perfect medium rare.

I also toasted a Costco ciabatta roll and brought out a tub of cream cheese with diced jalapenos.  If you don’t like heat then you can use plain cream cheese.

Please do not skip the part about toasting the ciabatta roll as the crunchy goodness makes a huge difference!

Flank Steak Sandwich Ingredients

Putting The World’s Best Flank Steak Sandwich Together!

Start by spreading a tablespoon of cream cheese on the top and bottom of the toasted ciabatta roll.  The rolls have lots of nooks and crannies, much like English muffins, and they really soak up the cream cheese.

Put about two tablespoons of caramelized onions on the bottom roll.

Take about three ounces of the flank steak, give it a rough chop, and place on top of the onions.

Pour a tablespoon of your favorite steak sauce on top of the meat and cover with the top bun.

Dig in and enjoy the steak feast!

Flank Steak Sandwich with Onions and Cream Cheese

Flank Steak Sandwich with Onions and Cream Cheese

Flank Steak Sandwich with Onions and Cream Cheese

The World's Best Flank Steak Sandwich!
Prep Time 5 minutes
Cook Time 20 minutes
Total Time 25 minutes
Course Main Course
Cuisine American
Calories 476 kcal


  • 3 ounces Medium Rare Flank Steak
  • 1 Vidalia Onion
  • 1 tbsp Butter
  • 1 Ciabatta Roll
  • 2 tbsp Cream Cheese
  • 1 tbsp Steak Sauce


  • Remove the skin from the onion and slice thinly.
  • Caramelize the onion slices in the butter over Medium heat for 15-20 minutes stirring often.
  • Cut the ciabatta roll in half and toast.
  • Add cream cheese to the top and bottom ciabatta roll halves.
  • Place two tablespoons of caramelized onions onto the roll, then top with the flank steak and streak sauce.
  • Dig in and try not to hurt yourself.
Keyword Flank Steak Sandwich

Good morning and welcome to the site dedicated to helping you find great products at Costco and other stores! My name is David Somerville and these are hands on reviews of products that I have bought and used or am seriously considering purchasing. I do most of my shopping at the Costco in Baton Rouge, Louisiana but will check out any other Costco warehouses I find while travelling. Please get in touch with any questions and let me know of any great products that deserved to be featured in this blog!

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