Heat the olive oil in a large skillet over medium heat. Add pork cubes; sear for 5 minutes per side or until golden.
In a large crock cooker, place potatoes, onions and apples. Cover with pork cubes then pour wine over all.
In a small bowl, mix together thyme, mustard, butter, salt and pepper; blend well then add on top of ingredients in slow cooker.
Cover and cook on LOW for 8 hours or until pork is fork-tender.