I enjoy travelling by train tremendously, so only train stations listed here.

Kyoto: Bento box including Kyoto Miso and real Kyoto pickles from the Bento stalls

Seoul: Kimchi Bokkumbap ( Kimchi fried rice & egg ) to eat on the train

Frankfurt: A portion of Currywurst & french fries from the meat shop in the underground shopping mall

London Euston: Pseudo Ploughman's ( Cheese & pickles baguette ) as only fast food counters have survived

Sapporo: Miso Ramen, of course

Paris Gare du Nord: Foie Gras for a tasty souvernir