How do we define a sandwich? Must it consist of two slices of bread with filling and be eaten as a light meal? Does it have to be cold or can it be hot? In actuality, it’s easier to define what’s not a sandwich – hot dog? Wouldn’t consider it. Bagel? Debatable. Burrito? Absolutely not. But in acceptance of all shapes, styles and sizes, we’ve rounded up the best of sarnies in London – from an American–style sub, and deli-counter staples, to a much-loved fish-finger sando and Vietnamese banh mi.