Celebrated on the Friday that falls between June 20 and June 26, the Swedish Midsummer (Midsommer) festival involves the joyful consumption of pickled herring, boiled red potatoes with sour cream, strawberries, and brännvin, a potent liquor distilled from spuds, grains, or wood cellulose.

As midsummer gives way to the dog days of August, Swedes opt for a more peculiar delectation — surströmming, or soured Baltic herring, which they eat during August parties known as surströmmingsskiva. The fermented fish comes in cans bulging with trapped gases that when opened release an overwhelming odor of piscine rot. Needless to say, surströmmingsskiva often take place outdoors.

Legend has it that the tradition of eating this surströmming began as a joke. Some time in the sixteenth century Swedish sailors en route to one exotic locale or another had only half the amount of salt needed to keep their cargo of fish fresh. The cargo naturally began to decompose. Luckily for the sailors, they came across a group of gullible Finnish islanders, on whom they unloaded the rotten cargo, saying it was a delicious delicacy. The waggish Swedes then sailed away. A year later they returned to the Finns’ island. Almost immediately upon dropping anchor the islanders begged them to part with more of the delicacy. Thinking their foul load might indeed have concealed untold gustatory pleasure, the Swedish sailors tasted the rotten fish. The rest, as they say, is culinary history.

The preparation of surströmming is something of an art. The herring are caught in spring and then fermented in barrels for one to two months. Then they are tinned. They are considered edible once enough gases have built up inside the tin to make the edges bulge into a rounded shape. The smell produced upon opening the can is described as resembling rancid butter, rotten eggs or vinegar.

Surströmming is often eaten with tunnbröd, or thin bread which comes in big square sheets. Northern Swedes favor a sandwich made using tunnbröd, butter, boiled and sliced potatoes, and, of course, a few generous slices of fermented fish. Southerners prefer their surströmming layered with diced onion, sour cream, chives, and sometimes a bit of tomato and dill. Connoisseurs debate over what is the proper drink for surströmming; beer, Schnapps, and milk are most frequently paired with it.

Should you wish to contribute a dish of herring (not necessarily of the fermented variety) to a Swedish summer festival, try this recipe for herring salad from the 1875 cookbook Things a Lady Would Like to Know Concerning Domestic Management and Expenditure. It’s economical, tasty and you need not eat it outdoors.

Herring Salad

An Excellent Herring Salad (Swedish Recipe). — Soak, skin, split, and bone a large Norway herring; lay the two sides along a dish, and slice them slopingly (or substitute for this one or two fine Dutch herrings). Arrange in symmetrical order over the fish slices of cooked beetroot, cold boiled potatoes, and pickled gherkins; then add 1 or 2 sharp apples chopped small, and the yolks and whites, separately minced, of some hard-boiled eggs, with anything else which may be at hand, and may serve to vary tastefully the decoration of the dish. Place these ingredients in small heaps of well-contrasting colours on the surface of the salad, and lay a border of curled celery leaves or parsley round the bowl.