Prepare the Peach & Plum Salsa: In a small saucepan, combine orange juice and balsamic vinegar. Bring to boiling; boil gently, uncovered, for 5 to 7 minutes or until reduced to 1/4 cup. Remove from heat; cool completely. In a medium bowl, combine plums and peaches. Add orange juice mixture; toss gently to coat. Cover with plastic wrap or foil and chill for 1 to 24 hours. Stir in snipped mint just before serving.