There is actually a way or strategy that goes behind layering a sandwich! The purpose is to prevent a sandwich from slipping or looking sloppy.
Follow these steps for a superb subway design:
Start by layering the denser textures, such as meat and cheese, first. They should be placed at the bottom of the sandwich.
Follow your layering with vegetables and any crunchy element. These should be carefully placed at the top for a stronger sub.
For a pro tip, try layering lettuce throughout the body of the sub to create an extra grip, this will prevent the sandwich filling from falling out!