How to Make It
In a medium bowl, mix the ketchup and mayonnaise. Add the green cabbage, onion, sweet gherkins, salt and pepper and toss to coat.
Melt 1 tablespoon of the butter in a large skillet. Add 2 slices of the rye bread to the skillet and top each with 2 slices of Jarlsberg cheese, then 4 slices of smoked turkey, about 1/2 cup of coleslaw, 2 more slices of Jarlsberg and another slice of bread. Cook the sandwiches over moderately low heat until the bottoms are toasted and the cheese on the bottom is melted, about 4 minutes. Turn the sandwiches over, press them down and add 1 more tablespoon of butter to the skillet. Cook until the second sides are browned, about 4 minutes. Transfer to plates and repeat with the remaining ingredients to make 2 more sandwiches.