Cola ham with maple & mustard glaze

INGREDIENTS

• 2kg unsmoked boneless gammon joint
• 2l cola (not diet)
• 1 carrot , chopped
• 1 onion , peeled and quartered
• 1 stick celery , chopped
• 1 cinnamon stick
• ½ tbsp peppercorns
• 1 bay leaf
• 150ml maple syrup
• 2 tbsp wholegrain mustard
• 2 tbsp red wine vinegar
• pinch of ground cloves or five-spice