Are waffles bread? Doughnuts? Deepfry batter? Ricecakes? Mushrooms? Potatoes? Peppers, tomatoes, cucumbers, eggplants, apples? Cabbage? Egg? Cheese?

I’ve seen all of these used to make what can only be called sandwiches. Bread is certainly popular for it’s dry and durable structure, but it’s not a requirement.