Real soused herring is made from exquisitely oily virgin herring which has eaten red feed. Soused herring is salted for just 24 hours. It is tenderised quickly, and then frozen to stop the (tenderisation) process.
Soused herring is a delicacy originating from the Netherlands. "Matje" means "young girl", and is derived from the same word as the German word "Mädchen". The herring is a North Sea herring smaller than Norwegian spring spawning herring, which is caught further to the north. To be made into soused herring, it has to have eaten red feed and have a percentage of fat of around 18–24 %.
The concept of soused herring is found as a delicacy in Sweden, Denmark and Germany, but only the Dutch make real Matjessild. The others are deemed to be "lookalikes".
Herring for soused herring is caught in the North Sea from mid-May to early July. Most of this herring is landed in Egersund, and production is carried out mainly in Egersund and Hirtshals by Dutch people. Only a small amount of soused herring production takes place in the Netherlands nowadays. Its main markets are the Netherlands and Germany. Unfortunately, the Norwegians have not yet discovered this delicacy.