Herrings are caught between the end of May and the beginning of July in the North Sea near Denmark or Norway, before the breeding season starts.
To protect against infection by nematodes of the genus Anisakis, European Union regulations state that fish should be frozen at −20 °C for at least 24 hours.
The Dutch newspaper Algemeen Dagblad has for more than thirty years organized a competition whereby the quality of soused herring was evaluated.
They require no further preparation after fillet and skin removal and can be eaten as a snack with finely sliced raw onion and pickles.
Soused herring dishes in Northern Germany are traditionally served with potatoes boiled in their skins, French beans, finely sliced fried bacon and onions.
It is also common in Germany to eat soused herring with sliced raw onions in a bread roll, in a dish called Matjesbrötchen.
In Sweden matjessill is traditionally served with boiled potatoes, sour cream, chopped chives, crisp bread and snaps.
Boiled eggs are popular together with this dish that is most traditionally served on Midsummer's Eve - Finland has a similar custom but silli is not associated with crisp bread.