Hapanvelli

Hapanvelli is a traditional South-Eastern Finnish dish that resembles pea soup but has a more sour flavour. It takes roughly an hour to prepare hapanvelli, which is made from a rye sourdough starter, potatoes and peas. It is traditionally served with a pat of butter and cold milk. Hapanvelli is a traditional dish of the Virolahti municipality which has the annual summertime Virolahti Week (Virolahti-viikko) during which hapanvelli is sold. There is also a contest during Virolahti Week in which the best cook gets the title of Miss Hapanvelli (Hapanvellimissi).

Source: Wikipedia