Preheat your grill to medium-high heat.
Season the flank steak with salt and black pepper on both sides.
In a small bowl, whisk together olive oil, balsamic vinegar, and honey.
Brush the marinade over the steak, reserving some for later.
Place the steak on the grill and cook for about 4-5 minutes on each side for medium-rare, or until desired doneness.
Remove the steak from the grill and let it rest for 5 minutes before slicing.
In a mixing bowl, combine cherry tomatoes, mozzarella cheese, and basil. Drizzle with the reserved marinade and toss gently.
Slice the steak against the grain and serve topped with the Caprese mixture.