Copenhagen is a city built on fish. Herring – or “sild” in Danish – has been fished in the waters off Denmark for thousands of years. It was the “silver of the sea”, a never-ending supply of food, and in turn wealth, that helped establish the Scandinavian city.
The herring is not a rare creature; different species of these oily fleshed, silver-coloured fish are found in abundance around the world. They can vary greatly in size, from tiddlers right up to almost half-a-metre in length, and they swim in huge schools that are netted in vast numbers in the Pacific, Atlantic and Indian oceans. But the type that helped make Copenhagen what it is today is the Baltic herring, a subspecies of the larger Atlantic herring, which tends to be no more than about 20cm long.
Baltic herring have been an important food in the region for millennia, and their influence can be seen in the shadows of Copenhagen’s past. Vikings lived in and around what is now modern-day Copenhagen, and evidence of established settlements on the site of the current city date back to the eleventh century. Then it was little more than a tiny fishing village called Havn (meaning harbour) on the Øresund, the narrow strait that runs between Denmark and Sweden into the Baltic Sea. Copenhagen’s name is an extension of that first settlement and translates as “merchant’s harbour”. Herring, passing through the narrow Øresund, were said to be so thick during September and October that they could be simply scooped from the water.
It wasn’t until the twelfth century, though, that the city really started to boom. Under Absalon, the Catholic bishop of nearby Roskilde who was given control of the fledgling town, cathedrals and fortifications were constructed. During this period, Copenhagen grew tenfold thanks largely due to the herring trade, which began to serve much of Europe’s Roman Catholic population with fish when they had to give up meat to fast for Lent. The city’s position as a preeminent centre in the region was finally cemented in 1343 when King Valdemar Atterdag named the city as the official Danish capital. Today, herring is still crucial to the city and the nation’s identity. It is a key ingredient that can be marinated, pickled, fried or smoked and is usually washed down with akvavit (aquavit), the Danish version of schnapps.
Herring is still cured using the traditional method. First the fish is filleted and boned, then these fillets are salted to remove water and dry them. The salt is then soaked out of the cured fillets before they are steeped in a marinade, usually made from a mixture of vinegar, salt and sugar with the addition of everything from peppercorns, bay leaves and onion, to mustard and dill and even curry paste to produce a dish called “karrysild”. Although a key part of Christmas and Midsummer celebrations, herring is eaten all year round; it usually provides a starter to most dinners and is a staple topping for the country’s famous open rye-bread sandwiches, the smørrebrød.
Beyond the capital, the Danish island of Bornholm, which lies closer to Sweden and Germany than mainland Denmark, is something of a food-lover’s paradise. Smoked herring is the order of the day here, and smokehouses – with their distinctive tall white square chimneys – are dotted across the island. A local dish called “Sol over Gudhjem" (“Sun above Gudhjem”), one the island’s picturesque little settlements, sees the fish smoked over alder wood and served with freshly baked rye bread, chopped chives and a raw egg yolk.
For those willing to go the extra mile, the miniscule island of Christianø that lies off Bornholm is said to make the best marinated herring available – they often feature in the nation’s Michelinstarred restaurants. The original recipe for the spice mix was brought back to the island from Asia by a Danish sailor, and is thought to include cloves, allspice and cinnamon. Today the marinade is a closely guarded secret: ask what’s in it and you’ll probably be told with a laugh that if they tell you they’ll have to kill you. In Denmark, herring is a serious business.