Trim fat from steak. Score both sides of steak in a diamond pattern, making shallow diagonal cuts at 1 inch intervals. Rub pepper into steak.
Place steak in resealable plastic bag set in a shallow dish. For marinade, in a small bowl stir together Italian dressing and mustard.
Pour marinade over steak; seal bag. Marinate in the refrigerator for 2 to 24 hours, turning bag occasionally.
Drain steak, reserving marinade. For a charcoal grill, grill steak on the rack of an uncovered grill directly over medium coals for 17 to 21 minutes for medium doneness (160°F), turning and brushing once with marinade halfway through grilling.
For a gas grill, preheat grill. Reduce heat to medium. Place steak on grill rack over heat. Cover and grill as above.
To serve, thinly slice steak diagonally across the grain. If desired, layer steak slices on Kaiser rolls.