For stuffing, stir together the chopped apple, bread crumbs, celery, raisins, walnuts, green onions and nutmeg. Stir in 1 tbsp. of apple juice or apple cider. Butterfly the pork tenderloin.

Cover meat with clear plastic wrap. Pound with a meat mallet to ¹⁄₂-inch thickness. Spread stuffing over meat. Roll up meat starting from one of the short sides. Tie with string to secure. Brush with some of the remaining 1 tbsp. apple juice. Place meat on a rack in a shallow roasting pan. Roast, uncovered, in a 350º F oven for 1 to 1 ¹⁄₄ hours or until meat is no longer pink, brushing with the remainder of the 1 tbsp. apple juice after 30 minutes.

Meanwhile, in a small saucepan stir together the ¹⁄₂ cup apple juice or apple cider, cornstarch and cinnamon. Cook and stir until thickened. Once bubbles start to form, cook and stir for 2 minutes more. Serve with roast.