Japan (Hokkaido as primary salmon roe production; September–October Keta salmon harvest)
Sujiko (whole salmon roe sac, cured in soy and mirin) and ikura (individual salmon roe spheres) represent the two expression forms of the same ingredient — the distinction being whether the delicate connective tissue membrane between eggs has been separated (ikura) or left intact (sujiko). Both derive from chum salmon (Oncorhynchus keta) and sockeye salmon harvested in Hokkaido and along Japan's Pacific coast during the September–October spawning migration. The fresh whole sac (sujiko) is cured immediately after harvest in a seasoned soy-mirin tare, producing a dense, intensely flavoured block of roe encased in its original membrane. Sujiko has a richer, more complex flavour than ikura because the membrane retains the interstitial fluid between eggs and the whole structure develops a unified flavour profile during curing. Ikura preparation requires the additional step of separating eggs from the membrane sac — traditionally by massaging the sac over a wire mesh screen in warm salt water, which dissolves the membrane without damaging the roe spheres. Fresh ikura season is brief: September–October for fresh domestic ikura; the rest of the year uses imported Pacific ikura. The characteristic 'pop' of premium ikura when bitten releases a rush of umami-rich salmon oil — this textural experience is as much the point as the flavour. Salt-cured ikura (shio-ikura) is considered by many Japanese enthusiasts to be superior to the more commercially common soy-marinated form, as the salt alone allows the salmon's natural flavour to express without the masking of soy.
Rich, briny, oceanic — salmon oil burst from intact membrane, umami sweetness of cured roe
{"Sujiko: whole sac, membrane intact, cured in soy-mirin — unified block with membrane-retained flavour","Ikura: individual spheres separated from membrane — membrane removal via warm salt water massage on screen","September–October domestic fresh harvest window; rest of year is imported Pacific or frozen","Fresh ikura 'pop' quality: membrane integrity produces the characteristic textural burst","Shio-ikura (salt only) considered purer expression than soy-marinated by Japanese connoisseurs"}
{"Ikura membrane removal: warm salt water (38°C, 2% salt), massage sac gently over screen, repeat with fresh water","Soy marinade for ikura: equal parts soy sauce and mirin + splash sake, 30 minutes only","Shio-ikura: 1.5% salt by weight applied to fresh ikura, rest 1 hour in refrigerator — pure salmon expression","Pairing: fresh ikura or sujiko with cold Hokkaido sake (mineral, clean) — the oceanic character matches perfectly"}
{"Using hot water for membrane separation — destroys the roe sphere membranes, producing broken, flat ikura","Over-marinating in soy — 30–60 minutes is sufficient; overnight marination produces overly dark, salty ikura","Serving imported ikura without disclosure when domestic fresh is the expectation at premium establishments","Cutting sujiko rather than pulling apart — the tearing motion releases more flavour"}
Japanese Cooking: A Simple Art — Shizuo Tsuji; The Japanese Kitchen — Hiroko Shimbo