Score meat by making shallow cuts at 1-inch intervals diagonally across steak in a diamond pattern. Repeat on the other side. Place meat in a plastic bag set in a shallow dish. For marinade, in a small bowl combine orange juice concentrate, the water, lime juice, ginger, oregano, salt, cayenne pepper, and garlic. Pour over meat; seal bag. Marinate in refrigerator for at least 30 minutes or up to 4 hours, turning bag occasionally.
Drain meat, reserving marinade. Place meat on the unheated rack of a broiler pan. Broil 3 to 4 inches from the heat for 15 to 18 minutes or until medium doneness (160 degree F), turning once. Thinly slice meat diagonally across the grain.
Wrap tortillas in foil. Place beside the broiler pan for the last 8 minutes of broiling meat. Meanwhile, pour reserved marinade into a medium saucepan. Stir in sweet pepper and onion. Bring to boiling; reduce heat. Simmer, covered, for 5 to 8 minutes or until vegetables are tender. To serve, spread each tortilla with some of the hoisin sauce. Top with Napa cabbage and beef. Using a slotted spoon, spoon pepper mixture over beef. Roll up. Makes 4 servings.