Using a food processor, crush the green peppercorns. In a medium bowl, whisk together the butter and steak sauce. Stir in the peppercorns, chives and lemon peel; season with salt and pepper. Transfer the butter mixture to a piece of parchment paper and shape into a log. Refrigerate until firm, about 2 hours.
Preheat the grill to medium. Brush the steaks with the olive oil and season with salt and pepper. Add to the grill, cover and cook for 6 minutes on each side for medium-rare. Top with the prepared butter.