Prepare the Gammon:
Place the gammon in a large pot with the onions, carrots, halved oranges, bay leaves, 10 cloves, cinnamon stick, and peppercorns
Cover with cold water and bring to a boil
Reduce heat and simmer for approximately 1 hour 15 minutes (allowing 30 minutes per 500g)
Preheat the Oven:
Set temperature to 180°C
Line a roasting tray with foil
Prepare for Glazing:
Remove gammon from cooking liquid and let cool slightly
Carefully remove the skin, leaving a good layer of fat
Score the fat in a diamond pattern
Stud each diamond intersection with a clove
Make the Glaze:
In a small saucepan, combine honey, orange zest and juice, mustard, soy sauce, brown sugar, and ground cinnamon
Simmer over medium heat for 5 minutes until slightly thickened
Glaze and Roast:
Place gammon in prepared roasting tray
Brush generously with glaze
Roast for 1 hour, basting every 15-20 minutes with remaining glaze
In the final 15 minutes, increase the temperature to 200°C for caramelization
Rest and Serve:
Remove from oven and let rest for 15-20 minutes before carving
Serve warm or cold with remaining pan juices