Preheat broiler. Trim fat from steak. Combine mustard, garlic powder, and pepper; spread over both sides of steak. Place steak on a broiler pan coated with cooking spray; cook 5 minutes on each side or until desired degree of doneness. Cut steak diagonally across grain into thin slices.
Combine steak, lettuce, and next 4 ingredients (lettuce through peas) in a bowl. Drizzle dressing over salad, and toss well.
Note: Substitute 1 (16-ounce) can cannellini beans for black-eyed peas, if desired.