01 - Lay out the rye bread slices on a clean cutting board or flat surface.
02 - Spread mustard evenly on one side of each bread slice, ensuring full coverage to the edges.
03 - Place a slice of Swiss cheese on two of the bread slices, directly over the mustard coating.
04 - Distribute half the corned beef slices evenly over each cheese-topped bread slice, folding if necessary for even thickness.
05 - Arrange pickle slices and lettuce leaves over the corned beef layer on each sandwich.
06 - Complete each sandwich by placing the remaining bread slices on top, mustard side facing inward.
07 - Slice each sandwich diagonally or vertically in half and serve immediately, or grill for a warm variation.