Surströmming is lightly salted fermented Baltic Sea herring traditional to Swedish cuisine since at least the 16th century. Surströmming or fermented herring is distinct from fried or pickled herring
How to eat surströmming like a local:
As the tin is pressurised, open the surströmming in a basin of water. Wash it, gut it, and wrap it in buttered ‘tunnbröd’ (a type of sweetened flat bread) with slices of almond potatoes and diced onion. Accompany with beer, snaps and lots of friends.
For those that don’t know:
You’re also supposed to open it underwater:
https://visitsweden.com/what-to-do/food-drink/swedish-kitchen/fermented-herring/
And if that doesn’t get the taste out of your mouth, nothing will.