On medium-low heat, saute the sauerkraut, several grinds of black pepper and caraway seeds until very dry and just slightly browning on the tips. Add the corned beef, and mix together with two spatulas - pushing away from you with one while pressing down on the other to break up the corned beef further. Add the Swiss cheese and stir together.
Butter one side of a slice of rye bread and place in an ungreased non-stick pan heated to medium-low. Add some more grated swiss cheese on the slice, then the warm filling on top of that. Add a spoonful of the creamy Russian dressing on top of the first layer, then the toasted piece of pumpernickel. Add a good slather of dressing on top of the toasted slice. Add another layer of the warm filling on top of the Russian dressing, along with a little pile of grated swiss cheese. Place the remaining slice of pumpernickel on top - outer layer buttered.
Now for the fun part - place a heavy weight on the sandwich - I use my “kitchen brick” (an actual brick covered by tin-foil) on the sandwich, with a small piece of parchment paper between. After only a couple of minutes, remove the weight, carefully turn the sandwich and weight down again. Leave in the pan for a few minutes, or until the bread is toasted. If you have a big enough pan you can do two sandwiches at the same time if not you must repeat the process listed above.
Cut the sandwich and serve with more of the Russian dressing on the side for dipping. Enjoy!