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 (if using cheese for this preparation).
04 - Distribute half the corned beef slices evenly over each cheese-topped bread slice, creating an even meat layer.
05 - Arrange pickle slices and lettuce leaves atop the corned beef layer as desired for texture and flavor balance.
06 - Complete the assembly by placing the remaining bread slices mustard-side down over the layered ingredients.
07 - Slice each sandwich diagonally or vertically in half and serve immediately for optimal freshness.