Preheat a panini grill or george forman style grill. (Alternatively, you can cook in a medium heat nonstick pan with a lid)
Layer the bread with cheese, sauerkraut, mustard and ham.
Place the sandwich on the panini grill or sandwich press. Close the lid; grill for 3 to 5 minutes or until cheese is melted and the sandwich is crispy. (or grill in a pan on medium heat on the stovetop covered with a lid until the bread is golden brown and the cheese is melted)
Notes
Pro Tip - watch the heat, don't be afraid to use a lower temperature so that the outside gradually comes to a golden brown while the cheese is melting.