Place the gammon steaks on a baking sheet, snip the rinds at intervals to prevent curling and cook under a preheated hot grill for 5 minutes on one side. Meanwhile, mix together all the topping ingredients in a small bowl.
Turn over the steaks and place a pineapple ring on top of each. Return to the grill and cook for 2 minutes, then top with the cheese mixture and cook for a further 2 minutes until the topping is golden. Serve with a mixed salad.