Grind the caraway seeds, paprika, garlic, mustard seeds, nutmeg and salt using a mortar and pestle. Rub the spice mix into the knuckles, place them on a baking tray and cover with foil.
To roast in the oven
Approx. 3 hours in the centre of an oven preheated to 150°C. Remove from the oven. Using two forks, loosen the meat from the bone and pull it away.
Bring the water to the boil with the vinegar, salt and sugar. Remove the pan from the heat, add the red cabbage and leave to infuse.
Spread the crème fraîche on half of the bread slices, top with meat and cheese, place on a baking tray lined with baking paper, place the rest of the slices of bread next to them.
Bake the slices of bread for approx. 10 mins. in the centre of an oven preheated to 180°C until the cheese begins to melt. Remove, arrange the radishes and drained red cabbage on top of the sandwiches, cover each one with a slice of bread, serve immediately.