Preheat the griddle. Turn your Blackstone to medium-high heat and let it fully preheat for 3 to 4 minutes.
Prep the ingredients. While the griddle heats, slice the ribeye as thin as possible (freeze it 30 minutes first for easier slicing). Slice the onion, bell pepper, and mushrooms. Toss the vegetables with 1 tablespoon of oil.
Sauté the vegetables. Drizzle the remaining oil onto the griddle and add the onions, peppers, and mushrooms to one side. Cook 4 to 5 minutes, stirring, until soft and lightly caramelized.
Cook the steak. Add the thinly sliced ribeye to the other side of the griddle. Use a metal spatula to chop and fold the meat as it cooks, about 3 to 4 minutes, until just cooked through.
Season and combine. Season the meat and vegetables with the Worcestershire sauce, garlic powder, salt, and pepper, then fold everything together.
Add the cheese. Divide the mixture into 4 roll-sized portions. Lay 2 slices of provolone over each portion and let it melt, about 1 minute.
Toast the rolls. Place the hoagie rolls face-down on the griddle for about 1 minute until lightly toasted.
Assemble and serve. Scoop each cheesy steak portion into a roll with your spatula. Serve immediately.