Prepare the Gammon: Place the gammon joint in a large stockpot and cover with cold water. Bring to a boil and discard the water to remove excess saltiness. Return the gammon to the pot.
Simmering: Add the quartered onion, star anise, whole cloves, coriander seeds, black peppercorns, bay leaves, and dry cider to the pot with the gammon. Top up with water if the cider does not fully cover the gammon. Bring to a boil, then reduce to a simmer. Cover and cook for about 2.5 hours, or until the meat is tender.
Preheat Oven: While the gammon is simmering, preheat your oven to 190°C (375°F, gas mark 5).
Prepare the Glaze: In a small bowl, mix together the dark brown sugar, clear honey, Dijon mustard, ground cinnamon, and ground allspice to create the glaze.
Baking: Once the gammon is cooked, remove it from the pot and let it cool slightly. Remove the skin, leaving a thin layer of fat. Score the fat in a diamond pattern and stud with cloves. Brush generously with the glaze. Bake in the preheated oven for 20-25 minutes, or until the glaze is bubbling and caramelized.
Rest and Serve: Let the gammon rest for 10-15 minutes before slicing. Serve warm with your choice of sides.
