Combine salad greens, chopped herbs and green onions; set aside. For dressing, combine lemon juice, mustard and olive oil. Toss salad mixture with dressing. Season salad with kosher salt and black pepper.
For each serving, cut one grilled flatbread into quarters. Plate the pieces, spoke-fashion, leaving plate center clear. Add 1 cup salad to center of plate; top with slivered oven-roasted tomatoes and BelGioioso Fresh Mozzarella Pearls.