Preheat oven to 400F degrees. Cook bacon to achieve desired doneness.
Toast sandwich bun in the toaster or in a grill pan, if desired.
Wash lettuce and prepare it, cutting it in fine shreds. Or use already prepared shredded lettuce.
Assemble the sandwich by applying mayonnaise to both the top and bottom bun pieces. Then add the lettuce, tomato, roasted turkey, bacon and Swiss cheese.