Hero Sandwich
This is just a submarine sandwich by another name, it turns out. This seems to be a regional New York term, dating from the 1930s (the same thing is referred to as a “Hoagie” in Philadelphia).
It’s not related to what’s in the sandwich, just the general concept of a long, cylindrical roll.
Why I Looked It Up
There was a NY Times Connections puzzle which grouped the words “bun,” “hero,” “roll,” and “wrap.”
I was confused, because I always through a hero sandwich referred to some combination of ingredients, whereas the Connections clue seemed to group them along the containers.