Preheat a grill.
In a small bowl, combine 2 tablespoons of olive oil with the lemon zest, rosemary, crushed red pepper, 1 tablespoon of sea salt and 1/2 teaspoon of pepper- Rub the mixture all over the steaks and let stand for 10 minutes.
Meanwhile, in a small bowl, mix the olives with the parsley, oregano, mint, capers, lemon juice, 1/2 teaspoon of pepper and the remaining 1/2 cup of olive oil.
Scrape the marinade off the steaks and season them with salt and pepper.
Grill the steaks over moderately high heat, turning them occasionally, about 10 minutes for medium-rare meat.
Let the steaks rest on a cutting board for 10 minutes, then thinly slice them crosswise.
Meanwhile, brush the cut sides of the rolls with olive oil and grill until toasted, about 1 minute.
Spoon half of the olive relish on the rolls and top with sliced steak and tomatoes.
Sprinkle lightly with salt and spoon the remaining relish on top.
Close the sandwiches and serve.