Asoused herring, Matjes (German, Swedish), is a specially mild salt herring, which is ripened using enzymes in a salty solution, or brine. In the Netherlands they are called maatjesharing which means maiden herring.
This process was developed in the middle ages by the Dutch. Herrings are caught between the end of May and the beginning of June in the North Sea near DenmarkorNorway, before the breeding season starts. This is because herrings at this time are unusually rich in oils (over 15%) and their roe and milt have not started to develop.
Through a cut in the throat, the gills are removed and the herring is only partly gutted, as some of the guts and, most importantly, the pancreas are left intact. The herrings are then placed in the brine for approximately 5 days, traditionally in oak casks.
The brine used for Dutch soused herring has a much lower salt content and is much milder in taste than the German Loggermatjes. To protect against threadworms (nematodes), which are fish pests, Dutch regulations mandate freezing to at least minus 45°C before salting. Soused herrings can therefore be produced throughout the year.
Whereas salt herrings need a salt content of 20%, soused herrings don’t have to be watered. As skin removal demands experience, filets or double filets should be attempted first. The soused herrings are silvery outside and pink inside when fresh, but should not be bought if they look grey and oily.
They require no further preparation after fillet and skin removal, and can be eaten as a between meal snack with a few onion rings.
Soused herring dishes in Northern Germany are traditionally served with potatoes boiled in their skins, French beans, finely sliced fried bacon and onions. Nevertheless it's more common in Germany to eat soused herring with sliced raw onions in bread, called Matjesbrötchen. Cream and/or yoghurt sauces are also used. Soused herrings are also good in salads or can be marinated.
