In 4-6 quart slow cooker, combine apples and onion. In small bowl, combine honey, mustard, coriander and salt. Spread on all sides of pork roast. Place pork over onions and apples.
Cook on low setting for 7 to 8 hours. Place on serving platter, cover with foil.
In a small saucepan, blend water and cornstarch until smooth. Add apple mixture and juices from the slow cooker; mix well. Cook over medium heat until mixture boils, stirring occasionally. Cut pork into slices. Serve with sauce.