This grilled ribeye steak sandwich is packed with flavor: tender caramelized onions and mushrooms, melted provolone, fresh arugula, and a garlicky roasted red pepper aioli, all on a warm, toasted ciabatta roll. It might just be the best sandwich you’ve ever tasted. The recipe takes around an hour from start to finish, but you can save time on the day-of by preparing the aioli and caramelized onions and mushrooms in advance.
INGREDIENTS
For the Caramelized Onions and Mushrooms
- 1 tbsp olive oil
- 3 tbsp butter, divided
- 8 oz sliced mushrooms (cremini or baby bella)
- 2 medium yellow onions
- 1/2 tsp kosher salt (or more to taste)
- 1/2 tsp granulated sugar (optional)
For the Roasted Red Pepper Aioli
- 4 garlic cloves
- 1 tsp kosher salt
- 1 cup mayonnaise
- 2 tbsp freshly squeezed lemon juice
- 4 tbsp olive oil
- 2 whole roasted red peppers
- Dash of cayenne pepper (to taste)
For the Sandwich
- 4 ciabatta rolls
- 4 thin-cut ribeye steaks (about 1.25–1.5 lbs total)
- Roasted red pepper aioli (double the batch if using a separate recipe; quantities listed above are accurate)
- Caramelized onions and mushrooms
- Fresh baby arugula
INSTRUCTIONS
Caramelized Onions and Mushrooms
- Prepare the onions by cutting them in half from root to tip, peeling, quartering, and slicing into 1/4″ strips.
- Preheat a large skillet or sauté pan over medium-high heat. Add the olive oil and 1 tbsp of butter; melt butter.
- Add mushrooms in a single layer and sprinkle with salt. Cook 2 minutes, flip, and cook another 2 minutes to brown the edges.
- Lower the heat to medium-low, add the remaining butter and onions, and cook uncovered for 30–45 minutes, stirring every 5 minutes, until the onions are soft, translucent, and caramel-colored. Add a little more butter if the mixture begins to look dry.
- Deglaze the pan with 1/4–1/3 cup of water, scraping any browned bits from the pan bottom. Adjust salt and add sugar if desired for extra sweetness.
Roasted Red Pepper Aioli
- While the onions caramelize, prepare the aioli. Finely mince or press the garlic and place it on a cutting board.
- Add the kosher salt, mash the garlic with the flat side of a chef’s knife into a paste.
- Dice the roasted red pepper, place it in a paper or clean kitchen towel, and squeeze out any excess liquid.
- In an immersion blender cup or mini food processor, combine garlic paste, mayonnaise, lemon juice, olive oil, roasted red peppers, and cayenne pepper. Blend until smooth.
Cooking the Steak and Rolls
- With about 15 minutes left on the onions, preheat the grill on high for 10 minutes.
- Brush both sides of the steak lightly with olive oil and season with kosher salt and cracked black pepper.
- Split the ciabatta rolls and butter the cut sides.
- Toast rolls by placing them butter-side down on the grill warming rack or, if unavailable, over a lower heat section. Toast for about 3 minutes until golden brown.
- Grill steaks over high heat for 30–45 seconds on each side. Remove and let rest briefly before slicing across the grain. Toss the steak slices in any remaining juices.
Assembling the Sandwich
- Spread 2 tbsp of aioli on each side of the rolls.
- On the bottom half, layer 1/4 of the steak slices, 1/4 of the caramelized onions and mushrooms, and 2 slices of provolone cheese. Return the sandwich bottoms to the grill for about 2 minutes, or until the cheese melts. (Turn off the grill now.)
- Top with a handful of arugula and the sauced top half of the roll.
- Slice in half if desired and enjoy!
