I don’t necessarily mean specific recipes, I mean concepts. A western sandwich is bread, (vegan) meat or cheese, sauce, tomato, something pickled, some salad, mostly, all layered and/or thinly sliced. Cross out maybe some of them for simplicity, like the mayo tomato or the british cheese and cucumber.
A döner kebap is sort of layered but everything but the protein layer is more of a mix up and not like tomato followed by onion or whatever.
A Banh Mi is sort of western of course, but it does a twist. The layers are there-ish, but they don’t matter so much. Sort of a hybrid between something like a kebap and a pita if you catch my drift.
What other sandwiches are there, conceptually?
Observe:
bread - wheat raised with yeast and left to rise
meat - probably smoked or salt-cured or something
cheese - milk, coagulated and aged
something pickled - a vegetable was left in an acidic brine
sauce - perhaps it is a fermented sauce
A pattern emerges:
From here we can see that the ur-sandwich is not about structure or ingredients, but rather the number of different preservation processes brought together into a single dish.
wine with bread is a sandwich, thus christ is a sandwich.
also
I think there has to be an unbroken linear arrangement. A sandwich means every ingredient has something above it and something beneath it, instead of all being mixed in together. Egg salad, tuna salad, etc. would all be considered single-ingredient sandwiches.