Portobello Philly Cheese Steak Sandwich

Name: Portobello Philly Cheese Steak Sandwich
Ingredients: 2 tablespoons minced fresh oregano, or 2 teaspoons dried; 4 whole-wheat buns, split and toasted; 1 tablespoon all-purpose flour; 3 ounces thinly sliced reduced-fat provolone cheese; 1 tablespoon reduced-sodium soy sauce; 1 large red bell pepper, thinly sliced; 1 medium onion, sliced; 4 large portobello mushrooms, stems and gills removed (see Tip), sliced; 1/2 teaspoon freshly ground pepper; 2 teaspoons extra-virgin olive oil; 1/4 cup vegetable broth, or reduced-sodium chicken broth