To make the dressing combine ½ cup of mayonnaise, 2 tablespoons of onion, 2 tablespoons of ketchup, 2 tablespoons of pickle relish, a pinch of paprika and a pinch of salt, in a small bowl.For the sandwiches lay out 8 slices of rye bread. Place a slice of cheese on each slice. Spread 1 tablespoon of the dressing on each slice. On four slices add beef. On the other four slices add sauerkraut. Pair one slice with corned beef and one with sauerkraut to create a sandwich.To cook the sandwiches, butter the side of each sandwich. Heat a skillet, over medium-low heat and place the sandwiches butter side down in it. Butter the other side well. Loosely cover them with foil. Cook until they turn brown on one side. Then flip them over. Cover again to cook until the other side becomes brown and the cheese has melted.