How to Make It
Place stock, potatoes, carrots, and turnip in a 6-quart slow cooker. Cover and cook on HIGH 1 hour.
Meanwhile, stir together rosemary, thyme, salt, and pepper in a small bowl. Rub pork with 1 tablespoon of the oil. Sprinkle pork all over with 2 tablespoons rosemary mixture, pressing to adhere. Heat remaining tablespoon oil in a large skillet over medium-high. Add pork, and cook until well browned, about 10 minutes, turning once halfway through.
Sprinkle vegetables in slow cooker with remaining rosemary mixture; add pork. Reduce heat to LOW, cover, and cook until a thermometer inserted in thickest portion of pork registers 135°F and vegetables are tender, about 3 hours. Remove to a cutting board, and let stand 10 minutes (pork temperature will rise as it stands). Place vegetables on a platter. Cut pork into 1/2-inch-thick slices, and arrange over vegetables. Stir together parsley, zest, and garlic; sprinkle over pork. Serve with juices from slow cooker.