In a medium bowl, mix the oil, soy sauce, vinegar, lemon juice, Worcestershire sauce, mustard, garlic, and ground black pepper. Place meat in a shallow glass dish. Pour marinade over the steak, turning meat to coat thoroughly. Cover, and refrigerate for 6 hours.
Preheat grill for medium-high heat.
Oil the grill grate. Place steaks on the grill, and discard the marinade. Grill meat for 5 minutes per side, or to desired doneness.