Surströmming is Baltic herring brined just enough to allow lactic-acid fermentation, then sealed in cans that continue fermenting on the shelf — the cans visibly bulge. The third Thursday of August is traditional opening day (surströmmingspremiären). It is one of the most pungent foods ever produced, with airline-banned levels of volatile sulfur — yet the actual eating, on tunnbröd (thin flatbread) with butter, almond potatoes, raw onion, and sometimes sour cream, is genuinely good. Northern Sweden takes the ritual seriously.
Open the can outdoors, ideally under water — the pressure release is real. Once exposed to air, the smell hits like a wall. The actual eating — fillets on buttered tunnbröd with potato, onion, sour cream — is gentler than the aroma promises.
The fermentation is driven mainly by salt-tolerant bacteria (chiefly Halanaerobium praevalens) and produces several dominant volatile odour compounds: hydrogen sulfide (rotten egg), propionic acid (pungent, sweaty), butyric acid (vomit / rancid cheese), acetic acid (vinegar), plus trimethylamine (the 'fishy' note of decomposing seafood). Its combined pungency ranks above natto and durian on standardized odour scales; eating it on a fat-rich base masks most of it.
Variations
Norrland fermentation runs 6 months in cans; some Finnish villages produce a similar but milder gravströmming buried in earth — same fish, different fermentation environment.
On the Palate
Where Surströmming sits in the Swedish flavor cloud
Ingredients
Serves 4
How it's made
5 steps · 30 min
- 16 min
Open the can OUTDOORS, ideally under water — the pressure is real. Rinse the fillets briefly in cold water to remove surface brine.
Watch outCrack the lid outdoors and under water — the can is bulging with gas, and it will spray brine several feet if you open it dry.
- 26 min
Have ready: 8 thin tunnbröd flatbreads, 8 small almond potatoes (boiled, peeled), 1 red onion finely diced, 200g sour cream, 50g butter, fresh dill.
- 36 min
Place a flatbread on each plate. Spread thinly with butter. Top with sliced potato, a fillet of surströmming (cut into 4cm strips), red onion, sour cream, dill.
Watch outBuild it on plenty of butter, potato and sour cream — the fat is what tames the smell so the bite tastes savory, not just pungent.
- 46 min
Roll the flatbread loosely into a wrap.
- 56 min
Eat immediately, washed down with cold beer or akvavit. Outdoors preferred.
Watch outEat it the moment it's rolled — sitting out only lets the aroma build; a cold drink cuts it on the way down.
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