How to Make It
Pat pork dry with paper towels; season on all sides with 1 1⁄2 teaspoons of the salt and 1⁄2 teaspoon of the pepper. Heat oil in a large skillet over medium-high. Add pork, and cook until browned on all sides, 10 to 12 minutes. Transfer to a 6-quart slow cooker. Pour off all but 2 tablespoons drippings in skillet, and add onion and garlic to hot drippings. Cook, stirring often, until slightly softened, 3 to 4 minutes. Transfer onion mixture to slow cooker with pork.
Add carrots, celery root, apple, cider, thyme, and 1⁄2 teaspoon of the salt to slow cooker. Cover; cook until vegetables are tender and pork is very tender, 5 hours on HIGH or 8 hours on LOW. Remove pork, and place on a platter. Using a slotted spoon, remove vegetables from liquid in slow cooker, and place in a bowl. Discard apple and thyme sprigs.
Skim fat from surface of liquid; discard. Whisk water and cornstarch in a small bowl. Stir cornstarch mixture into liquid in slow cooker, and cover and cook on HIGH until thickened, 30 minutes. Meanwhile, shred pork into bite-size pieces, discarding any large pieces of fat. Sprinkle with 1⁄2 teaspoon of the salt. Stir remaining 1⁄2 teaspoon salt and 1⁄4 teaspoon pepper into gravy in slow cooker. Serve hot cooked noodles with vegetables, pork, and gravy. Garnish with thyme.