The rule for a Kitakami korokke is a list of four things: futago taro, Japanese Black beef, pork raised in the prefecture, and asparagus. Include all four and you may call it by the name. Everything else is left to the cook, which means no two shops in the city produce the same object.

The taro is the part you notice. Croquettes elsewhere are potato, dry and floury, holding their shape. Taro is sticky and slightly glutinous, so cutting one open produces a pull rather than a crumble, and the inside is closer to paste than to mash. It is not what your hands expect from the shape.

It was assembled deliberately. Cooks in Kitakami wanted the town to have something of its own and built it out of local produce, and in 2010 it went to the national B-grade gourmet event as the first entry from Iwate.

Four rules is a good number. Fix too much and every shop makes the identical thing and the point evaporates. Fix too little and the name means nothing. Four ingredients and no further instructions gives you a name that holds and a city full of variations at the same time, which is why the local tourism association is able to hand out a map of where to eat them.