1In food processor bowl with metal blade, place orange pieces. Cover; process, using quick on-and-off motions, about 15 seconds or until finely chopped. Add cranberries; process until finely chopped.
2In nonmetal container, combine cranberry mixture, sugar, walnuts and mint. Stir in liqueur. Let stand at least 3 hours before serving to blend flavors. Store in refrigerator up to 1 week.