1 Heat oil in a large non-stick 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.
2 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.
3 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.
12 ounces beef top sirloin, trimmed of fat and cut into ¼-inch strips
1 tablespoon minced fresh ginger
1 large onion, slivered (1½-2 cups)
1 small red bell pepper, diced (1 cup)
1 pound broccoli florets, (about 4 cups)
1 Combine ¼ cup broth, cornstarch, soy sauce, marmalade, oyster sauce, vinegar and chile-garlic sauce in a small bowl; mix well.
2 Heat 1 teaspoon oil in a wok or large non-stick skillet over high heat. Add half the beef; stir-fry until browned, about 2 minutes. Transfer to a plate. Stir-fry the remaining beef in 1 teaspoon oil; transfer to the plate.
3 Add the remaining 2 teaspoons oil to the wok. Add ginger and stir-fry until fragrant, 10 to 20 seconds. Add onion; stir-fry for 30 seconds. Add bell pepper and broccoli; stir-fry for 30 seconds. Pour in the remaining ¼ cup broth, cover and cook until the vegetables are crisp-tender, 2 to 4 minutes. Push the vegetables to the sides. Stir the sauce mixture and add it to the wok. Cook, stirring, until the sauce becomes thick and translucent. Stir the vegetables into the sauce and return the beef to the wok; toss to coat. Serve immediately.