1    20 oz top sirloin steak

      2 tb Vegetable oil

    1/2 ts Dried leaf oregano, crushed

    1/2 ts Salt

    1/4 ts Coarsely ground pepper

    1/4 c  Orange juice

      1 tb Lime juice

      2 ts Cider vinegar

      2    Orange slices, 1/2" thick

  Place steak in a shallow glass baking dish. Rub with oil on each side.
  Sprinkle with oregano, salt and pepper. Sprinkle orange juice, lime
  juice, and vinegar over the steak. Cover and refrigerate overnight for
  best flavor or several hours, turning occasionally.
  To cook, bring meat to room temperature. Prepare and preheat charcoal
  grill (or gas grill). Drain meat, reserving marinade. Place steak on
  grill. Top with orange slices. Occasionally spoon reserved marinade
  over steaks as they cook. Grill 3-4 minutes on each side, or until
  medium- rare. Cook longer if desired. Remove orange slices to turn
  steak. Replace orange slices on top of steak.