That’s quite disputed.
One of the more likely theories states that the bun idea together with the ground meat steak originated in Hamburg, where it was a variant of the common “Rundstück warm”, which has been around since 200 years ago or so.
It’s less disputed than most food origins. I looked up your rundstuck warm food. Dunno why you’re trying to make that argument, because because that sure looks nothing like a hamburger, nor does it get eaten like one. That it didn’t use ground beef aside, it being covered in gravy is a dead giveaway.
That’s quite disputed.
One of the more likely theories states that the bun idea together with the ground meat steak originated in Hamburg, where it was a variant of the common “Rundstück warm”, which has been around since 200 years ago or so.
It’s less disputed than most food origins. I looked up your rundstuck warm food. Dunno why you’re trying to make that argument, because because that sure looks nothing like a hamburger, nor does it get eaten like one. That it didn’t use ground beef aside, it being covered in gravy is a dead giveaway.