The breaded pork tenderloin is defined by a deliberate mismatch: the meat is far larger than the bun. A pork loin cutlet is pounded thin and wide until it dwarfs the soft bun it sits on, overhanging it by inches on every side, and that overhang is not an accident or excess. It is the point of the sandwich. The bun is a handle and a center bite; the cutlet is the meal, and the design openly admits the bread is outmatched, which is the inverse of how almost every other American sandwich is built.
The craft is in the pounding and the fry. A cut of pork loin is butterflied and beaten with a mallet until it is a thin, even sheet two or three times the diameter of the bun, which is what lets it cook fast and stay tender rather than going to a dry slab. It is dredged and breaded into a craggy coating and fried hot so the shell sets crisp and the thin meat cooks through before the crust darkens too far. The soft bun is chosen precisely because it cannot compete: a pillowy, slightly sweet roll that yields against the hard fried cutlet rather than fighting it, dressed only with the cold, sharp basics, pickle, mustard, raw onion, lettuce, that cut the fried fat without adding bulk. The structural reality is that most of the eating happens off the bread entirely, working in from the edges of the overhang toward the part that is actually a sandwich, which is a build that only makes sense where it comes from.
The variations are codified around the cut and the cook. The grilled tenderloin drops the breading for a leaner, charred version that changes the sandwich completely; the cracker-crumb coating runs against the seasoned-flour coating as a matter of regional preference; the loaded build piles on cheese and the works while keeping the oversized cutlet fixed. These belong to the dense long tail of regional American specialties built around a structural decision a national chain would never accept, and each deserves its own article rather than being crowded in here.