Combine vinegar and garlic in a large zip-top plastic freezer bag; add steak, turning to coat. Seal and let stand at room temperature 30 minutes, turning steak occasionally.
Remove steak from marinade, discarding marinade. Sprinkle evenly with pepper and salt.
Grill, covered with grill lid, over medium-high heat (350° to 400°) 5 to 7 minutes on each side or to desired degree of doneness. Let stand 10 minutes; cut into thin slices diagonally across the grain.