Heat a nonstick grill pan over medium-high heat.
To prepare steak, combine the first 5 ingredients; rub evenly over both sides of steak. Coat grill pan with cooking spray. Cook steak 4 minutes on each side or until desired degree of doneness. Remove from pan; let stand 5 minutes. Cut steak diagonally across grain into thin slices.
While steak stands, prepare salad. Place bread slices on a baking sheet. Broil 2 minutes on each side or until lightly browned. Rub cut sides of garlic halves over bread slices. Cut bread into (3/4-inch) cubes. Combine bread cubes, tomatoes, cucumber, onion, and lettuce in a large bowl. Add dressing, tossing gently to coat. Divide salad evenly among 4 plates; top with steak.