The Sandwich Club is the format itself, not any one café's reading of it: three slices of toasted bread, two stacked layers, a stack tall enough that the architecture is the defining feature. The standard build is poultry, lettuce, tomato, a cured pork, and a creamy dressing, divided across two tiers of filling and bound by the middle slice of toast. What defines it is not the ingredient list, which barely varies, but the structure: a double-decker held together by a third slice in the middle, cut into quarters and pinned so the geometry survives service.
The craft is structural before it is anything else. Two layers of filling collapse under their own weight without a slab of bread between them, so the middle slice is load-bearing, not decorative, and the toasting matters as much as the toppings: toast that has gone soft cannot do the job and the whole stack slumps. The pile is deliberately taller than the mouth, which is why the sandwich is built to be quartered and pinned rather than eaten head-on, each wedge exposing its cross-section so the layers read at a glance. This sets the constraint clearly: every component has to be sliced thin and laid flat, because anything bulky destabilizes a stack already fighting gravity, and the dressing has to bind without soaking, because a saturated middle slice fails first. It is a sandwich whose engineering is the recipe.
Variations are swaps inside a fixed frame, the same architecture spoken with different fillings. Swap the poultry for a smoked fish and you have a lighter read; drop the meat for vegetables and the structure carries a meatless version under the same name; the Parisian café tradition takes this exact format and quietly upgrades its materials, a regional accent worth its own treatment in Club Sandwich Parisien. The Sandwich Club's contribution to the catalog is the format in its general form: the triple-slice, double-decker, quartered-and-pinned structure that every regional version inherits before it changes a single ingredient.