Grill ham steaks on one side for about 3 minutes. Turn and grill other side for 1½ minutes. Arrange segments of mustard fruit on top of steaks and place under grill for 1 to 2 minutes more. Remove from grill; place steaks on a heated serving dish and pour heated honey over them. Garnish each steak with 2 or 3 walnuts. Serve immediately.