Take a look outside. Are you in Iceland? Now take a look at your calendar. Is it Þorri—the coldest and most brutal month of the year, which stretches from late January to late February? 

If the answer to both of these questions is yes, the time is ripe for a Þorrablót—a feast that calls for piles of smoked lamb, endless Brennivín, and a variety of other delicacies, including sour rams’ testicles.

Traditional Þorrablót fare hearkens back to the days before refrigerators, when Icelanders stored perishable food for the long winter by pickling, smoking, drying, or rotting it. To prepare this particular dish, cooks wash the testicles thoroughly, then remove the outer membranes and boil them. They then pickle the glands for several months in whey, changing it regularly to avoid bacterial growth. Once the balls reach the right level of acidity, they are pressed together into a rectangular block, which Þorrablót revelers will then slice and eat.

Rams’ testicles gained extra cachet in the late 1950s, when the Reykjavik restaurant Naustið began serving them—along with other traditional countryside dishes like fermented shark (hákarl) and boiled sheep’s head (svið)—as a winter delicacy. 

Today, Icelanders around the world celebrate Þorrablót at festivals and in their homes, and you can find pickled rams’ testicles in certain Icelandic supermarkets in midwinter. According to one grocer, they are consistently the most popular traditional winter dish, and have gained popularity in America and Asia as well. ‘Tis the season!