The Newark hot dog is not one dog but two, and the second dog is the part that makes it a Newark institution rather than a regional variant. A single deep-fried frankfurter is a snack; a pair of them stood upright inside a pocket cut from a round of pizza bread is a meal a working city built its lunch around. The defining decision is the doubling inside the bread vessel: the two dogs lean against each other and against the walls of the hollowed loaf, and the fried potatoes pack down the gap so the whole load holds itself in compression. A standard split bun could carry one dog along a hinge. It could not carry two upright with a quarter pound of fried potatoes wedged around them, which is exactly why Newark abandoned the bun for a pocket.
The craft is in the pocket and the order it is packed. The bread is a round Italian pizza loaf, and a quarter or half of it is torn or cut open into a deep cavity rather than split, because the sandwich is loaded vertically and eaten from the open end. The crumb has to be sturdy enough to be a container under a heavy, oily, two-dog load and still tear cleanly on the bite. The frankfurters are fried until the casings blister and snap, a harder surface than a griddle leaves, and they go in standing. Then the fried potatoes, cut in rounds or wedges and crisped, are driven down around and between them, with fried peppers and onions worked in for sweetness and to bind the mass. Built in that order the dogs anchor the center, the potatoes lock them, and nothing slides out of the open end before the sandwich is gone. This is stand-at-the-counter food engineered around the deep fryer, and the doubled load is the whole reason the pocket exists.
The Newark dog sits in the national hot dog map beside the other builds that rebuild the bread and the cargo for a local argument: the Chicago order with its forbidden ketchup, the coney under its fine meat sauce, the smokier half-smoke, the bacon-wrapped Sonoran, the slaw dog, and the single-dog Italian build that shares the pizza bread but stops at one. Each is a codified sandwich with its own rules and deserves its own article rather than being crowded in here.