Cut the tomatoes half, then brush with 2 tablespoons of the oil and season with salt and pepper. Grill the tomatoes on all sides until slightly charred and soft. Remove the tomatoes from the grill, chop and place in a bowl. Add the remaining 3 tablespoons of oil, onion, vinegar, basil and parsley and season with salt and pepper. Serve warm or at room temperature.
For the beef:
Heat the grill to high.
Place the steak on a flat surface. Combine the cheese, parsley, oregano and garlic in a small bowl. Brush the steak on the side facing up with 2 tablespoons of the oil and season with salt and pepper. Sprinkle the cheese mixture evenly over the steak, leaving a 1/2-inch border around the sides.
Starting with the long end, tightly roll the meat up like a jelly roll and tightly tie with the butcher's twine on the ends and in the center. Brush the entire outside of the steak with the oil and season with salt and pepper. Place on the grill, seam-side up and grill until golden brown on all sides, about 10 to 12 minutes. Remove from the grill and let rest 10 minutes before slicing into 1/2-inch thick slices. Serve several slices per person topped with some of the relish.