2 teaspoons extra-virgin olive oil
1 medium onion, sliced
4 large portobello mushrooms, stems and gills removed, sliced
1 large red bell pepper, thinly sliced
2 tablespoons minced fresh oregano, or 2 teaspoons dried
1/2 teaspoon freshly ground pepper
1 tablespoon all-purpose flour
1/4 cup vegetable broth, or reduced-sodium chicken broth
1 tablespoon reduced-sodium soy sauce
3 ounces thinly sliced reduced-fat provolone cheese
4 whole-wheat buns, split and toasted
Heat oil in a large nonstick skillet over medium-high heat. Add onion and cook, stirring often, until soft and beginning to brown, 2 to 3 minutes. Add mushrooms, bell pepper, oregano and pepper and cook, stirring often, until the vegetables are wilted and soft, about 7 minutes.
Reduce heat to low; sprinkle the vegetables with flour and stir to coat. Stir in broth and soy sauce; bring to a simmer. Remove from the heat, lay cheese slices on top of the vegetables, cover and let stand until melted, 1 to 2 minutes.
Divide the mixture into 4 portions with a spatula, leaving the melted cheese layer on top. Scoop a portion onto each toasted bun and serve immediately.
Per serving: 268 calories; 10 g fat ( 4 g sat , 4 g mono ); 15 mg cholesterol; 35 g carbohydrates; 13 g protein; 7 g fiber; 561 mg sodium; 704 mg potassium.