On December 23rd, Icelanders celebrate Þorláksmessa (or the Mass of Saint Þorlákur). As it is the last day of fasting, people eat fish rather than meat. The traditional fish to eat on this day is fermented skate that smells of ammonia due to the process of pickling and putrefying the fish (eating skate fresh can be harmful due to enzymes found in the fish). Since the smell is so strong, some apartment buildings in Iceland have banned the cooking of this dish inside the buildings. As a result, some people will go out to restaurants to indulge in this delicacy or others will try to contain the odor by cooking it outside on a barbecue.
The dish is traditionally served with potatoes, turnips, and melted sheep fat and accompanied with Brennivín. Since the odor and taste is so strong, many Icelanders have strong feelings of either support or disdain for this tradition. A study in 2012 by Market and Media Research found that around 40% of Icelanders partake in this tradition. I think I would opt for the smoked lamb and skip the fermented skate!
Photo is from Iceland Magazine.