Stage 1: Place the joint in a large pot or casserole with the bay leaves & garlic. Cover with water and bring to the boil. Put on the lid and simmer for 3 hours. Skim off the scummy froth from time to time and replenish the water as necessary.
Stage 2: About 15 minutes before the steaming time is up preheat the oven to 190°C. Crush the 2 star anise then blend in a mixing bowl with the mustard, maple syrup & sugar.
Drain the gammon, and when it's cooled, remove the skin but retain the fat into which you cut a diamond pattern.
Place the joint into a roasting tin, coat with ¾ of the syrup mix and put into the oven for 15 minutes.
Stage 3: Take the joint from the oven, carefully place the 6 plums (halved) around it and push the 10 star anise into the skin. Pour the remaining syrup over the plums. Return to the oven for another quarter of an hour.