After boiling in a pot of salted water for an hour, the steaming sheep's head is plated up for the evening's Thorrablot buffet, an Icelandic winter festival rooted in Norse mythology, featuring traditional - and sometimes gut-turning - dishes.

In addition to the sheep's head, the menu consists of blood sausage, sliced sheep testicles, liver sausage, smoked lamb, herring, dried fish, sour whale blubber and fermented shark.

Thorrablot dinners celebrate Thorri, the personification of winter or frost in Norse mythology and representing the fourth month of winter in the old Norse calendar - usually falling between January and February. 

This year, Thorri falls between January 25 and February 23.

With family, colleagues or friends, Icelanders share a meal in Thorri's honour with the old-fashioned dishes - usually fermented, smoked or dried as a way of preserving food for long periods - and all consumed with generous amounts of alcohol and drinking songs. 

'Smelly, but delicious'

The odour of ammonia from the fermented shark, cut into small cubes, tickles nose hairs as soon as the jar is cracked open.

"It's like French cheese: it's really smelly but when you eat it, it's really delicious," laughs Perla Runarsdottir, the owner of Cafe Loki, a restaurant serving traditional Icelandic cuisine in the heart of Reykjavik with a view over the imposing Hallgrimskirkja church.

"I love the flavour, it brings back memories from my childhood and it enables us to reconnect with our roots," says Sigurdur Ingi Hauksson, 47, a guest who by day works at Iceland's emergency operator 112.

A must for outsiders visiting Iceland, the fabled dish of fermented shark is best accompanied by a glass of Brennivin, a strong, schnapps-like alcohol made out of fermented potatoes and flavoured with caraway.

"It's good to rinse your throat to wash down this strange taste," suggests Perla, a 47-year-old mother of three.

Diced mixed vegetables, steamed and mashed potatoes, and dark rye bread round out the ample meal.  

Around the table, six of Perla's friends are enjoying their dinner.

"This is my seventh (Thorri meal) this year but there can never be too many for me," says Thorsteinn Gunnlaugsson, erupting in laughter.

The first Thorrablot festivals date back to the 19th century, but the idea of connecting the festival to traditional food took off in the 1960s when Naustid, a now-defunct Reykjavik restaurant, launched its dinners.

Nowadays most Icelanders enjoy a Thorrablot about once or twice during the month.

"It's a good reason for everyone to get together during the long winter nights," says Sigurdur.

In the depth of winter, Reykjavik gets just four hours of sunlight, but by February it has grown to more than nine hours.