Preheat the oven to low, ready to keep the ham warm later.
Trim any fat from the steaks. Heat the butter in a large frying pan until sizzling, add the cloves, then fry two ham steaks over fairly high heat for 3 minutes each side, until browned. Transfer to a serving dish and put in the oven to keep warm.
Cook the other two steaks and add them to the serving dish.
Pour the sherry into the frying pan and bring to the boil, scraping up the sediment from the bottom of the pan. Stir in the mustard and boil for 2 minutes until the sauce has reduced. Discard the cloves, then pour the sauce over the ham.
Serve with rice and a vegetable such as broccoli or Celery and Apple, Wild Rice and Fennel Salad.