This is underrated outside of the north east, never mind internationally, but pease pudding. Most people in the UK haven't tried it, and a lot that have have had terrible pease pudding but done well it's delicious.

In case you're unfamiliar with it, it's a gravy/spread (it solidifies when cold so you can spread it on sandwiches) made from yellow split peas, boiled until they're completely smooth. What makes it excellent though is that you use water in which you've previously boiled a ham, so the peas take on a delightful salty, hammy flavour. You can then use it as an accompaniment to said ham.