Mix 1 tablespoon of the Seasoning Mix and ranch dressing in small bowl. Refrigerate until ready to serve.
Mix remaining Seasoning Mix, oil and lime juice in small bowl until well blended. Place steak and vegetables in separate large resealable plastic bags. Add 2 tablespoons of the marinade to vegetables. Add remaining marinade to steak; turn to coat well.
Refrigerate 30 minutes or longer for extra flavor. Remove steak and vegetables from marinade. Discard any remaining marinade.
Broil or grill steak over medium heat 6 to 8 minutes per side or until desired doneness. Place vegetables in heated skillet or grill pan on medium-high heat. Cook and stir 3 minutes or until tender. Slice steak across the grain into thin slices. Arrange steak and vegetables over lettuce on serving platter. Drizzle with prepared dressing. Serve with assorted toppings, if desired.