Steak Sandwich with Garlic Aioli & Caramelized Onions
This savory steak sandwich features tender, seared flank steak, sweet caramelized onions, and melty provolone, all layered on crispy ciabatta with a creamy homemade garlic aioli. Simple yet packed with flavor, it’s the perfect sandwich for any occasion.
Ingredients
For the Garlic Aioli
- 1/2 cup mayonaise
- 3 cloves garlic minced
- 1 tsp dijon mustard
- 1 tablespoon lemon juice
- salt and pepper to taste
- drizzle olive oil
- fresh parsley, chopped optional
For the Sandwich
- ½ large onion (white, yellow or red) thinly sliced
- olive oil for cooking
- 8-10 ounces flank steak
- salt and pepper to season
- 2 ciabatta rolls sliced in half
- 2 slices provolone cheese
- handful fresh arugula
Instructions
Make the Garlic Aioli
- In a small bowl, mix together the mayo, minced garlic, Dijon mustard, lemon juice, olive oil, and a pinch of salt and pepper. If using fresh parsley, stir that in too. Set aside to let the flavors develop.
Caramelize the Onions
- In a skillet over low heat, add a drizzle of olive oil and the thinly sliced onions. Stir occasionally and let them cook low and slow until soft, golden, and caramelized—this usually takes around 20 minutes.
Tenderize and Cook the Steak
- Place the flank steak between two sheets of plastic wrap or parchment paper and gently pound it with a meat mallet to tenderize. Season both sides generously with salt and pepper. Heat a skillet over medium-high heat and sear the steak until it reaches your desired doneness. For medium-rare, aim for an internal temp of 125°F. Let it rest for 5–10 minutes before slicing thinly
Prep the Ciabatta Rolls
- While the onions are caramelizing and the steak is cooking, preheat your oven to 350°F. Place the ciabatta rolls cut-side up on a baking sheet. Drizzle with olive oil and sprinkle with garlic powder and a dash of garlic salt. Toast in the oven for 5–7 minutes until lightly crisped.
Assemble the Sandwiches
- Layer the sliced steak onto the bottom halves of the toasted ciabatta. Top with provolone cheese and place under the broiler for about 1 minute, just until the cheese is melted. Remove from the oven, spread garlic aioli on the top halves of the rolls, and add the caramelized onions and a handful of arugula. Close the sandwiches and serve immediately.
Enjoy every juicy, melty, garlicky bite!
Notes
- Tenderizing the Steak: Don’t skip the tenderizing step! Using a mallet to pound the flank steak helps break down the fibers, making it more tender and easier to bite into. This is especially important for a sandwich, where you want that buttery, melt-in-your-mouth texture.
- Resting the Steak: After searing, let the steak rest for at least 5–10 minutes before slicing. This helps the juices redistribute throughout the meat, keeping it moist and flavorful.
- Onion Caramelization: Be patient when caramelizing the onions! Low and slow is the key to achieving that perfect golden color and sweet flavor. Stir occasionally to avoid burning.
- Provolone Cheese: If you prefer a different cheese, feel free to swap the provolone for something like cheddar or mozzarella—just make sure it melts well!
- Ciabatta Rolls: Toasting the ciabatta adds crunch and warmth, creating a perfect base for the juicy steak. If you prefer a softer roll, skip the oven and use fresh ciabatta. My go to and absolute favorite ciabatta are these rolls from Trader Joes!