Surströmming is a fermented fish product made with strömming, a type of herring, sourced from the cold waters of the Baltic Sea, usually in spring. The fish is salted, cleaned, and allowed to ferment before being canned. This herring is defined by a rather distinctive and strong odor that results from its fermentation process, which is initiated by a type of lactic acid enzyme in the herring’s spine and it doesn’t cease even after the fish has been canned.
Despite its strong smell, the fermented herring has an interesting flavor that is a perfect mix of piquant, savory, and acidic. There’s also an annual surströmming festival (surströmmingsskiva) in Alfta, Halsingland, which traditionally takes place on the third Thursday in August, when a significant number of enthusiastic Swedes and fans of this fermented fish delicacy gather to savor the contents of numerous bulging cans of surströmming.