Prepare mashed potatoes according to package directions, using 1 1/3 cups milk.
Combine parsley, sage, salt, and pepper in a small bowl; set aside. Combine water and cornstarch in a bowl; stir well, and set aside.
Trim fat from pork. Slice tenderloin crosswise into 1/2-inch slices, and flatten to 1/4-inch thickness. Rub 2 tablespoons parsley mixture evenly over pork.
Heat 1 1/2 teaspoons oil in a large nonstick skillet over medium-high heat. Add half of pork slices, and cook 2 minutes on each side or until browned. Transfer pork slices to a plate; cover tightly with foil. Repeat with remaining oil and pork slices.
Add onion and carrot to skillet; cook 6 minutes, stirring often. Add cider and remaining parsley mixture. Cover, reduce heat, and simmer 5 minutes or until vegetables are tender. Return pork to skillet. Cook, uncovered, over medium-high heat 4 minutes or until liquid reduces to a light syrup. Add reserved cornstarch mixture to pan. Bring to a boil; cook 1 minute, stirring constantly, until thick and bubbly. Serve over mashed potatoes.