Scatter onion, garlic and thyme sprigs over the base of a 4.5L (18-cup) slow cooker.
Combine the honey, mustard, sugar, sauces, stock and apple juice in a jug. Pour into the slow cooker. Place the pork belly on top. Cover and cook on High for 5 hours 30 minutes or until pork is very tender. Add apple wedges. Cover and cook for 30 minutes or until the apple is just tender.
Use tongs to transfer the pork and apple to a large baking tray. Remove excess skin and fat from the pork. Use 2 forks to shred the pork. Return the pork and apple to the slow cooker and warm through. Sprinkle with thyme leaves and season, to serve.
