In the same skillet, saute the onion, garlic and sugar until onion is caramelized and tender. Stir in the apple juice, cranberry juice, cranberries, mustard and rosemary. Bring to a boil. Reduce heat; simmer, uncovered, for 5-6 minutes or until sauce is reduced by half.
Return pork to pan; heat through. Sprinkle with additional cranberries and rosemary if desired.