Preheat oven to 375 degrees F and large sauté pan over high heat for 1-2 minutes.
Spray pan with cooking spray. Place pepper stir-fry and mushrooms in pan. Sauté 3-4 minutes, stirring occasionally.
Add steak, steak seasoning and Worcestershire sauce. Cover and cook 5-7 minutes, breaking meat up as it cooks.
While steak is cooking, cut bar cheese into 1/8-inch slices. Place pizza crust on baking sheet and spray with cooking spray.
Place steak mixture in colander and drain well by pressing with back of spoon. Spread steak mixture in center of crust, leaving a 1-inch border. Place bar cheese on top of steak mixture and sprinkle with shredded cheese.
Bake for 12-15 minutes, or until golden brown.
Cut into 6 wedges and serve.