1. Rub seasoning over fish; sprinkle with salt. Heat a large nonstick skillet over medium heat; coat pan with cooking spray. Add fillets. Cook 4 minutes on each side or until fish flakes easily when tested with a fork.
2. While fish cooks, combine grated cucumber and dressing. Slice bread in half lengthwise; cut into 4 portions. On bottom half of each portion, place 1 lettuce leaf, 1 salmon fillet, 3 cucumber slices, and 2 tablespoons cucumber-ranch dressing. Top with remaining half of bread.