Sandwich me Tyri kai Zampon is the ham-and-cheese sandwich, the baseline of the Greek counter case and the one most people mean when they ask for a plain sandwich. It is national, cold-built unless someone runs it through a press, and deliberately unremarkable. The angle is precisely that it is the reference point: every other filling in the case is judged against how a good ham-and-cheese eats, so the question is not what makes it special but whether the kitchen bothered to do the simple thing well.
The build is two ingredients and bread, which means there is nowhere to hide. Zampon is sliced cooked ham; tyri is usually a mild yellow melting cheese. They go into a soft roll or sliced sandwich loaf, often with the cut faces buttered or spread thinly with mayonnaise, and frequently with a leaf of lettuce and a round or two of tomato. Good execution means ham folded rather than packed flat so it eats tender, cheese in enough quantity to register, fresh bread with structure, and the cut faces protected by a spread so the bread does not dry out or go soggy from the tomato. Sloppy execution is a single thin slice of each pressed into a dense layer, stale bread, no spread, and a thick wet tomato slice undermining the whole thing. When it is pressed or toasted, the failure mode shifts: not hot enough to melt the cheese, or hot enough to dry the ham to leather.
It shifts in modest, familiar ways. The cold version with lettuce and tomato is the everyday default. The toasted or pressed version, with the cheese melted and the bread crisp, is the most common upgrade and the one most counters do well. Some add mustard or a thin layer of skordalia for sharpness against the mild cheese. The pressed Greek toast as its own street format, tost, is a distinct thing with its own conventions and deserves its own article rather than being crowded in here. On its own, Sandwich me Tyri kai Zampon is the honest measure of a counter: get the bread, the spread, and the proportions right and the plainest sandwich in the case is genuinely good.