- Combine teriyaki marinade & sauce and wine; pour over roast and onions in shallow, non-metal baking dish. Cover pan tightly and refrigerate 8 hours or overnight.
- Reserving onions mixture, remove roast from marinade about 45 minutes before cooking. Sprinkle both sides of roast with meat tenderizer and pepper; pierce meat deeply and thoroughly with fork. Let stand 30 minutes.
- Cook roast on grill 4 to 5 inches from hot coals 25 minutes (for medium-rare), or to desired doneness, turning over occasionally.
- Meanwhile, drain onions; sauté in hot oil in medium skillet over medium heat 5 minutes. Reduce heat to low; cover and cook 5 minutes longer, or until tender, stirring occasionally.
- Cut roast across grain into thin slices and serve with onions.