Rollmops are pickled

Pickling

Pickling, also known as brining or corning is the process of preserving food by anaerobic fermentation in brine to produce lactic acid, or marinating and storing it in an acid solution, usually vinegar . The resulting food is called a pickle. This procedure gives the food a salty or sour taste...

 herring

Herring

Herring is an oily fish of the genus Clupea, found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Three species of Clupea are recognized. The main taxa, the Atlantic herring and the Pacific herring may each be divided into subspecies...

 fillets

Fillet (cut)

A fillet is a cut or slice of boneless meat or fish.- Meat :In the case of beef, in the USA, the term most often refers to beef tenderloin, especially filet mignon.- Chicken :...

, rolled (hence the name) into a cylindrical

Cylinder (geometry)

A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder...

 shape around slices of onion

Onion

The onion , also known as the bulb onion, common onion and garden onion, is the most widely cultivated species of the genus Allium. The genus Allium also contains a number of other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion The onion...

, pickled gherkin

Gherkin

The gherkin is a fruit similar in form and nutritional value to a cucumber. Gherkins and cucumbers belong to the same species , but are from different cultivar groups....

, or green olive with pimento. Rollmops can be served held together with one or two small wooden skewers.

Rollmops are usually bought ready-to-eat, in jars or tubs. The marinade additionally contains water, white vinegar, and salt; it may also contain sugar or other sweetening agent, 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 2–3 weeks if kept cool.

Origins and etymology

In English, the word is singular, i.e. "rollmop" the plural being "rollmops" or "rollmop herrings" though sometimes treated as both singular and plural.
In German, the word Rollmops is singular with the umlaut

Germanic umlaut

In linguistics, umlaut is a process whereby a vowel is pronounced more like a following vowel or semivowel. The term umlaut was originally coined and is used principally in connection with the study of the Germanic languages...

-plural form Rollmöpse.
The name 'rollmops' is German

German language

German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....

 in origin, originating from the words rollen (to roll) and Mops (German name of pug

Pug

The pug is a "toy" breed of dog with a wrinkly, short-muzzled face, and curled tail. The breed has a fine, glossy coat that comes in a variety of colors, and a compact square body with well-developed muscle. They have been described as multum in parvo , referring to the pug's personality and...

 dogs / "blockhead").

Pickled herrings have been a staple in Northern Europe since Medieval times, being a way to store and transport fish, especially necessary in meatless periods like Lent

Lent

In the Christian tradition, Lent is the period of the liturgical year from Ash Wednesday to Easter. The traditional purpose of Lent is the preparation of the believer – through prayer, repentance, almsgiving and self-denial – for the annual commemoration during Holy Week of the Death and...

. The herrings would be prepared, then packed in barrels for storage or transportation.

Rollmops grew popular throughout Germany during the Biedermeier

Biedermeier

In Central Europe, the Biedermeier era refers to the middle-class sensibilities of the historical period between 1815, the year of the Congress of Vienna at the end of the Napoleonic Wars, and 1848, the year of the European revolutions...

 period of the early 19th century and were known as a particular specialty of Berlin, like the similar pickled herring dish Bismarckhering. A crucial factor in their popularity was the development of the long-range railway network, which allowed the transport of herring from the North and Baltic Seas to the interior. The fish was pickled to preserve it and transported in wooden barrels. In pubs in Old Berlin, it was common to have high-rising glass display cases (Hungerturm, meaning "hunger tower") on the bar to present ready-to-eat dishes like lard bread, salt eggs, meatballs, mettwurst (bacon sausage) and of course rollmops. At the present time, rollmops are commonly served as part of the German Katerfrühstück (hangover breakfast) which is believed to restore some electrolytes.

Distribution

Rollmops are found in Dutch, Belgian, English, Scottish, German, Estonian, Latvian, Scandinavian, Czech, Slovak, Kashubian

Kashubian

Kashubian can refer to:* Pertaining to Kashubia, a region of north-central Poland* Kashubians, an ethnic group of north-central Poland* Kashubian language-See also:*Kashubian alphabet*Kashubian Landscape Park*Kashubian studies...

, Polish, Brazilian, and South African cuisine, among others.