How to Make It
Heat a grill pan over medium-high.
Coat steak with 1 tablespoon oil; sprinkle with garlic powder, 1/4 teaspoon salt, and 1/4 teaspoon pepper. Add steak to pan; cook 4 minutes on each side. Place steak on a cutting board.
Place squash, onion, and bell pepper in a large bowl. Add 1 tablespoon oil, 1/4 teaspoon salt, and 1/8 teaspoon pepper; toss. Arrange vegetables on grill pan; cook 4 minutes. Turn and cook 2 minutes. Chop into bite-size pieces.
Combine remaining 2 tablespoons oil, remaining 1/4 teaspoon salt, remaining 1/8 teaspoon pepper, vinegar, sugar, and cheese. Divide vegetables and tomatoes among 4 plates. Cut steak into thin slices; top with vegetables and vinaigrette.