Slice roast across grain into 1/4 inch thick slices. Combine miso, mirin, soy sauce, vinegar, sugar and sesame oil. Place beef in self sealing plastic bag; add marinade, turn bag, and massage to coat. Refrigerate 4 hours. Remove meat from marinade; wipe off excess. Grill over hot coals 1 to 1 1/2 minutes on each side or until seared. Serve hot with ginger-teriyaki sauce, over noodles or rice. SAUCE: Place all ingredients into a saucepan and bring to a boil. Lower heat and simmer into a light syrupy consistency.