Grilled Steak and Portobello Stacks

Directions

1. In a small bowl, combine 2 tablespoons oil and herbes de Provence. Rub over tenderloin; cover and refrigerate for 2 hours. Place mushrooms in a small bowl; toss with vinegar and remaining oil. Cover and refrigerate until grilling.
2. In a large skillet, cook the onion, sugar, salt and pepper in oil over medium heat for 15-20 minutes or until golden brown, stirring frequently. Remove from the heat; stir in vinegar. Set aside.
3. In a small bowl, combine the sauce ingredients. Cover and refrigerate until serving.
4. Grill tenderloin and mushrooms, covered, over medium heat for 8-10 minutes on each side or until meat reaches desired doneness (for medium-rare, a thermometer should read 135°; medium, 140°; medium-well, 145°) and mushrooms are tender. Let tenderloin stand for 10 minutes.
5. Meanwhile, brush both sides of bread with butter. Grill over medium heat for 1 minute on each side or until browned. Toss salad greens with vinaigrette. Cut tenderloin and mushrooms into thin slices.
6. Divide mushrooms among four slices of bread. Layer with roasted peppers, greens and another slice of bread. Top each with onion mixture and beef. Spread sauce over remaining slices of bread; place over beef. Cut each sandwich diagonally in half.