Whisk olive oil, balsamic vinegar, Dijon mustard, honey, garlic, salt, and pepper until smooth.

Transfer half of the mixture into a clean jar and refrigerate. Reserve for finishing the dish later.

Place flank steak into a zip top bag. Add remaining marinade and coat evenly. Refrigerate for 4 to 6 hours.

Remove steak from the refrigerator 20 to 30 minutes before grilling.

Heat grill to high temperature, around 500°F (260°C). Pat steak dry before cooking.

Cook 4 to 6 minutes per side until desired internal temperature:

Medium: 135°F to 140°F (57°C to 60°C)

Allow steak to rest 5 to 10 minutes under loose foil.

Cut thin slices against the grain for better tenderness.

Arrange sliced steak on a serving plate. Add tomatoes, mozzarella, and basil.

Drizzle reserved dressing over the top. Add balsamic glaze and optional sea salt before serving.

Do not marinate longer than 12 hours.

Fresh mozzarella works better than shredded mozzarella.

Slice flank steak against the grain to avoid chewy texture.

Skirt steak works as a substitute.