Photograph: Keiko Oihawa
Put the gammon in a large saucepan. Add the vegetables and peppercorns. Cover with water and bring slowly up to the boil, skimming off any impurities. Simmer, uncovered, very gently for 1 hour 15 minutes. Remove from the heat and leave to cool in the liquid for 2 hours.
Preheat the oven to 190°C, fan 170°C, gas 5. Once the gammon is tepid, remove it from the liquid and carefully cut away the rind, leaving the fat. Score the fat into diamonds and stud with cloves. Put a large sheet of nonstick baking paper in the bottom of a roasting tin. Place the gammon on the paper, fat side up.
Mix together the honey, sugar and mustard powder – set over a low heat to blend them if necessary. Roughly spoon the lumpy honey mixture over the fat and cut surfaces – don't worry, it will melt and even out as it cooks. Spoon over the orange juice and bake in the oven for 45 minutes. Baste occasionally with the sugary juices, then transfer to a serving plate.
Meanwhile, for the spiced pineapple and orange relish, place the orange juice, zest, raisins, cloves, cinnamon and sugar in a non-reactive (not aluminium or cast iron) saucepan. Set over a low heat, bring to the boil and simmer for 10 minutes.
Top and tail the pineapple. Cut away the skin and ‘eyes'. Quarter the peeled pineapple lengthways and cut away and discard the tough inner core. Dice the pineapple flesh. Tip into the orange juice mixture, return to the boil and heat through for about 5 minutes. The pineapple should be barely cooked. Strain the pineapple and transfer to a bowl. Return the juice to the pan and boil vigorously until it forms a sticky sauce. Discard the spices and mix the sauce into the strained pineapple. Serve the pineapple and orange relish alongside the ham.
Get ahead: if serving cold, prepare the gammon up to 3 days in advance; chill. If serving hot, the gammon can be poached 2-3 hours in advance. The spiced pineapple relish can be made a few hours before it’s needed.
Kitchen secret: you can serve both the sugar-glazed gammon and spiced pineapple and orange relish hot, warm or cold. Save the gammon broth for a lentil or pea soup.