The humble, dependable, versatile sandwich is one of those foods that can be life-alteringly delicious or a devastating disappointment. At its most basic level, a sandwich consists of fillings placed between layers of bread. Seems simple enough. And yet, delve into each step in the making of a sandwich and you will find a hundred ways it can go wrong. The bread element is crucial, and there are so many factors to consider: texture, size, and density, to name a few.