I'm in Liverpool.
I have lived all over and you can only get Sui Mais here (that I have for nd anyway.)No one else outside of Liverpool seems to have heard of them.
They are pork and prawn dumplings but bigger and better and not won tons.
Recently went to Cardiff and I had a corned beef and mash thing from the chippy that was a welsh thing. It definitely began with R but it was regional to that area I think. It was fabulous.
What do you have that you don't see anywhere else?