Healthier Philly Cheesesteak Sandwiches

Name: Healthier Philly Cheesesteak Sandwiches
Prep time: 10 min
Cook time: 20 min
Total time: 30 min
Cuisine: American
Ingredients: 12 ounces flank steak (sliced across grain into thin strips. ); 1/4 teaspoon kosher salt; 1/4 teaspoon black pepper; 1 cup sliced mushrooms ((3 ounces)); 1 medium onion (sliced thin); 1 bell pepper (sliced thin); 1 Tablespoon olive oil; 1 clove garlic (minced); 1/2 teaspoon Worcestershire sauce; 1/2 teaspoon low-sodium sauce; 1 Tablespoon butter; 2 teaspoons flour; 1/2 cup milk (2 %); 1 ounce provolone cheese (grated); 2 tablespoons grated Parmigiano-Reggiano; 1/4 teaspoon dry mustard; 4 hoagie rolls (toasted)