Rollmops

Rollmops are pickled herring fillets, rolled into a cylindrical shape, often around a savoury filling. The filling usually consists of onion and sliced pickled gherkin. Rollmops are often skewered with a cocktail skewer. Rollmops are usually bought ready-to-eat, in jars or tubs. The brine additionally consists of water, white vinegar, and salt; it may also contain sugar or other sweetening agents, onion rings, peppercorns and mustard seeds. Rollmops can be eaten cold, without unrolling, or on bread. After the jar has been opened, they will usually keep for two to three weeks if kept cool or refrigerated. Rollmops are sometimes served with Labskaus.

Source: Wikipedia