Back in the day, Vikings were catching and preserving fish with the help of salt and vinegar. Today the Danes still enjoy this kind of fish, especially herring that was prepared this way. It is served in almost all snack bars and restaurants and it is often eaten by the locals at home. An especially popular way to serve it is as an ingredient in a smørrebrød. You'll also find a huge variety of pickled herring in grocery stores. Pickled Herring is usually eaten for lunch and is almost always accompanied by rye bread and some butter. It's also often served with eggs, capers and onions.