Sprinkle pork chops with pepper. Place pork chops in 3 1/2- to 4-quart slow cooker. Sprinkle with garlic. Pour soup over pork chops.
Cover; cook on Low heat setting 7 to 8 hours or until the pork is fork-tender. Remove pork chops from slow cooker and place on plate; cover to keep warm.
About 30 minutes before serving, make rice as directed on package. Stir together cornstarch and water. Stir cornstarch mixture into mushroom sauce in slow cooker. Heat in slow cooker 5 minutes. Serve sauce over pork chops and rice.