Place the gammon in a large pan along with the vegetables and spices. Pour in the cold water, bring to a gentle simmer then cook for around 80 minutes (allow 20 minutes per 500g). Check for an internal temperature of at least 70°C using a meat thermometer.
Remove from the pan and place on a board. Remove the skin from the joint and trim the fat leaving a thin layer.
Combine the glaze ingredients (maple syrup, rose harissa, marmalade, and dark soy sauce). Microwave for 30 seconds, then liberally brush all over the ham.
Bake in a preheated oven set at 200°C/180°C fan for 20 minutes.
Rest for at least 30 minutes before carving
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