Position oven rack 4 inches from broiler and set oven to broil. Line a large rimmed sheet pan with foil, and spray with non-stick cooking spray.

In a large bowl, toss onions, peppers, and mushrooms with 1 tablespoon of oil and 1 tablespoon of steak seasoning. Transfer to the sheet pan, leaving room for the steak.

In the same bowl, mix the remaining oil and steak seasoning. Rub mixture into steak and transfer steak to sheet pan with vegetables.

Broil for 8-12 minutes, or until thermometer inserted in thickest part of steak reads 135 degrees (for medium). Transfer steak to a cutting board, covering with foil to keep warm. Stir vegetables and return to oven for 3-4 more minutes, or until tender.

Thinly slice steak against the grain. Return to pan with vegetables, mixing to combine. Top with shredded cheese. Broil for 1-2 more minutes, or until cheese is melted.

Serve cheese steak mixture in rolls or sandwich buns.