01 - Rub the steak with olive oil, Worcestershire sauce, salt, and pepper in a shallow dish. Let marinate at room temperature for 10 minutes.
02 - Heat a skillet over medium heat. Add butter and sauté onions and bell pepper (if using) until soft and caramelized, about 8–10 minutes. Transfer to a plate.
03 - Increase skillet heat to high. Sear the steak for 2–3 minutes per side for medium-rare, or until desired doneness is reached.
04 - Transfer the steak to a cutting board and let rest for 5 minutes. Slice thinly against the grain.
05 - Slice the rolls open and toast lightly.
06 - Mix mayonnaise and Dijon mustard together. Spread the mixture inside the toasted rolls.
07 - Layer arugula, tomato slices, caramelized onions, and bell peppers onto the bottom halves of the rolls.
08 - Top with sliced steak and cheese. Optionally place under a broiler for 1–2 minutes to melt the cheese.
09 - Close the sandwiches, slice in half, and serve immediately.