According to tradition, the third Thursday in August is the day on which the Swedish delicacy hits the supermarket shelves and can be eaten.
The herring is caught early in spring, left to ferment and then canned. Once opened, it’s famous for its extremely pungent odor, so many Swedes prefer to eat it outdoors. The herring tradition goes back a long way - the first record of the dish being eaten is in 1544.
Last year, major airlines including British Airways and Air France banned the herring from their flights, classifying the pressurised tins as explosive goods.