The ebi fry sando keeps the prawn whole, and that single fact decides everything else about it. Ebi fry is a whole prawn, butterflied and straightened, dredged and coated in coarse panko and deep-fried so it arches gold and crisp with the tail often left on as a handle. Slid onto shokupan with tartar sauce, it makes a sandwich whose defining quality is that you are biting through one intact piece of shrimp, not a uniform patty. The crust, the prawn, and the tartar need each other in a specific order: the panko gives the crack, the prawn gives a clean snap of sweet shellfish, and the cold tartar binds the two and keeps the whole thing from being merely fried. Mince the prawn and it becomes a different sandwich entirely.
The craft is in keeping the prawn straight, crisp, and whole through assembly. The shrimp is deveined and scored along the belly so it does not curl, then coated in coarse panko and fried hot and fast so the crust sets deep gold while the flesh stays just-cooked and springy rather than rubbery. One or two large prawns are laid along the bread so the cut crosses the body and the cross section shows a ring of white shrimp inside its crust. The shokupan is fresh and soft, often spread thin with butter or mustard to seal it, and the tartar, a chopped-egg and pickle mayonnaise, is applied generously enough to season every bite without sogging the crust before it reaches you. Shredded cabbage sometimes adds a cool crunch under the prawn. A good one snaps audibly and tastes distinctly of clean shrimp against tangy tartar. A poor one is overcooked to rubber inside a thick limp coating, or so wet with sauce the crust is gone before the first bite lands.
The variations turn on size and dressing. Larger prawns give a more dramatic cross section and a meatier bite; a sauce swap toward tonkatsu sauce or a chuno sauce pulls it toward the katsu sando shelf; the ebi katsu sando, built from minced shrimp formed into a patty, is the smoother and more uniform cousin and a genuinely separate sandwich. Each of those deserves its own article rather than being crowded in here.