WHISK together marinade ingredients in shallow dish. Add seafood and sliced mushrooms; turn to coat. Cover and refrigerate 30 minutes.
COMBINE all vinaigrette ingredients except oil in a blender or food processor. Process on high speed until the mixture is well blended. With the motor running, carefully pour in the olive oil in a steady stream. Set aside.
SPRAY grill pan or sauté pan with no-stick cooking spray; heat to medium high heat. Remove seafood and mushrooms from marinade; discard marinade. Grill shrimp and scallops 2 to 3 minutes per side or until seafood is cooked through and has browned highlights. Remove from pan and set aside. Add mushrooms; grill 4 to 5 minutes, turning once. Remove from pan.
ARRANGE salad ingredients on a medium platter. Top with grilled seafood and mushrooms. Drizzle dressing as desired over the salad. Top with the Parmesan cheese if desired.