I apologise if this has been discussed ad infinitum already.
I recall - with my notoriously poor memory - that when I moved back from the US to England in the mid-1970s, I thought it odd that English people served “hot dogs” (that were often buttered, and used English pork sausages rather than frankfurters, and were usually crap) with the bun cut vertically through the smooth top of the bun, rather than across the bun.
Eating hot dogs tonight, it occurred to me that cutting them downwards seemed more sensible, as it allowed the base of the bun to act as a “hinge” and prevented the two halves from separating so readily.
Then casting my mind back to a trip to NYC a couple of years ago, I think that maybe the buns of the vendors’ dogs were indeed cut vertically.
Irritatingly, Wikipedia has two photographs of hot dogs in their buns, and one bun is cut vertically, and one horizontally.
So, which is the correct way?