Season both sides of the steak with coarse salt, massaging it thoroughly into the surface. Place the meat into a shallow dish or resealable plastic bag.

Combine balsamic vinegar, Worcestershire sauce, brown sugar, minced garlic, and Dijon mustard in a bowl. Whisk until fully blended, then pour the marinade over the steak, ensuring it is completely coated. Flip the meat as needed. Cover and refrigerate for no less than 30 minutes, preferably for over 2 hours for deeper flavor.

While the steak marinates, prepare the Caprese topping by gently mixing the cherry tomatoes, mozzarella balls, basil, balsamic vinegar, olive oil, sea salt, and a squeeze of fresh lemon juice in a bowl. Store in the refrigerator until needed.

Allow the marinated steak to sit at room temperature for 10 to 15 minutes before cooking.

Heat 2 tablespoons of olive oil in a large cast-iron skillet over medium-high heat. Once the oil is shimmering, add the steak. Sear each side for 4 to 7 minutes, depending on the thickness, or until the internal temperature reaches 135–140ºF for medium-rare.

Remove the steak from the pan and allow it to rest for a minimum of 10 minutes. Slice thinly against the grain and serve topped with the prepared Caprese salad.