Place all the ingredients for the gammon into a pot large and fill it with water until the gammon is submerged.
Bring the water to a boil then turn down the heat to low and gently simmer the gammon for 2 hours.
Heat a medium-size pot over medium heat.
Heat the oil and butter, then add the onion and fry until softened.
Add the garlic and fry for a minute until fragrant.
Add the two jams, mustard and balsamic and whisk well to combine.
Season to taste and set aside.
Add the diced bacon to a large frying pan over medium heat.
Cook the bacon slowly to render out the fat and crisp it up.
Use a slotted spoon to remove the bacon onto a piece of kitchen towel to drain and keep as much of the bacon fat in the pan as possible.
Add the halved Brussels sprouts cut side down into the pan and return it to the heat.
Cook the Brussels sprouts cut side down until they are caramelised then stir and continue cooking until they are soft but still retain a slight crunch.
You may have to do this in two batches or use two frying pans.
Toss the Brussels sprouts with the cooked bacon and lemon zest then season to taste.
After 2 hours remove the gammon from the pot and place it onto a rack to cool slightly.
Preheat the oven to 200 ºC.
Cut the netting off the gammon then using carefully remove the skin with a sharp knife.
Try to keep as much of the fat under the skin on the gammon as possible.
Score the fat in lines about 1 cm apart.
Place the gammon on a roasting rack and use a pastry brush to paint it with a generous amount of glaze
Bake the gammon for 15 minutes, then give it another painting of glaze and bake for a further 15 minutes until the outside has caramelised.
Remove from the oven and let the gammon rest for 15 minutes before carving.
Serve with Brussels sprouts and your other favourite festive sides.
