Get a griddle/fry pan heated on medium low heat.
Spread mayonnaise on all four slices of bread.
Heat corned beef until warm and spread on two slices of bread.
Lay two slices of Swiss cheese on each slice of bread over the corned beef.
Measure out 1 cup of sauerkraut and place in paper towels
Squeeze all the water/juice out of the sauerkraut.
Separate and spread the sauerkraut evenly over the Swiss cheese on both sandwiches.
Put the other slice of Rye bread on the top.
Spread softened butter on the outside of both slices of bread.
Spread a thin layer of mayonnaise on top of the butter.
Place butter side down on the warm griddle.
Set the timer for 4 minutes.
Butter the other side of bread and spread a thin layer of mayonnaise, too.
When the timer goes off, flip the sandwich.
Place a large lid on top of the sandwiches.
Set the timer for 4 minutes.
When the timer goes off, flip the sandwich and place the lid on again.
Set the timer for another 4 minutes.
Flip for the last time and set the timer for four minutes.
Make sure you place the lid on during the last four minutes.
Take the sandwiches off the heat, slice and serve.