To prepare dressing, combine the first 6 ingredients in a small bowl, stirring well with a whisk.
To prepare salad, sprinkle both sides of steak with salt and pepper. Place steak on a grill rack coated with cooking spray; grill for 4 minutes on each side or until desired degree of doneness. Let stand 5 minutes. Cut steak diagonally across grain into thin slices.
Combine lettuce and remaining ingredients in a large bowl. Add steak to bowl. Drizzle salad mixture with dressing mixture; toss to coat. Serve immediately.