Soused herring is raw herring soaked in a mild preserving liquid. It can be raw herring in a mild vinegar pickle or Dutch brined herring. As well as vinegar, the marinade might contain cider, wine or tea, sugar, herbs (usually bay leaf), spices (usually mace), and chopped onion. The word 'soused' can also describe a marinated herring that has been cooked. The herring is usually baked in the (vinegar) marinade (but can be fried and then soaked in the marinade). It is served cold. This is usual in Scotland, Wales and Ireland. The soused herring (maatjesharing or just maatjes in Dutch, or Matjes/matjes in German and Swedish respectively) is an especially mild salt herring, which is made from young immature herrings. The herrings are ripened for a couple of days in oak barrels in a salty solution, or brine. The pancreatic enzymes which support the ripening make this version of salt herring especially mild and soft. Raw herring pickled in vinegar are called rollmops. As of 2015, within the EU, Dutch made Hollandse Nieuwe, Holländischer Matjes and Hollandse maatjesharing have TSG Certification and German produced Glückstädter Matjes, produced in Schleswig-Holstein has PGI certification. As a pickled herring it can form one course of the traditional twelve-dish Christmas Eve supper in Poland. History This process of preparing herring (known as "gibbing") was developed in the Middle Ages by the Dutch. 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. This is because herrings at this time are unusually rich in oils (over 15%) and their roe and milt have not started to develop. 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 infection by nematodes of the genus Anisakis, European Union regulations state that fish should be frozen at −20 °C for at least 24 hours. In the modern day, soused herrings can therefore be produced throughout the year. Preparation Through a cut in the throat, the gills and part of the gullet are removed from the herring, eliminating any bitter taste. The liver and pancreas are left in the fish during the salt-curing process because they release enzymes essential for flavor. The herrings are then placed in the brine for approximately 5 days, traditionally in oak