KO EN Japanese Appetizer⏱ 15 minEdit history

Ruibe (Salmon Sliced and Eaten Frozen)

Name: Ruibe (Salmon Sliced and Eaten Frozen)
Prep time: 15 min
Total time: 15 min
Yield: 4 servings
Cuisine: Japanese
Ingredients: 300 g salmon; 2 tbsp soy sauce; 1 tsp wasabi; 50 g daikon; 4 shiso or perilla leaves

The Ainu frozen salmon of Hokkaido. Salmon left outside in winter until frozen through is sliced thin while still frozen and eaten with soy sauce and wasabi before it thaws. Raw-meat dishes such as yukhoe and carpaccio freeze only the surface, for the knife, and warn against freezing through, because the thaw makes the flesh weep. Ruibe freezes it through and removes the thaw. The same freeze is also what deals with the parasites raw salmon can carry.

Ingredients

4servings

Ruibe (4 people)
salmon · skinned, pin-boned fillet; buy it already frozen and sold for eating raw300 g
soy sauce2 tbsp
wasabi1 tsp
To serve
daikon · finely shredded50 g
shiso or perilla leaves4

Steps

Buy salmon sold already frozen for eating raw. If you freeze it yourself it needs −20°C or colder for at least seven days (the US FDA rule for fish eaten raw); a home freezer is usually set to −18°C and cannot be relied on to meet it.
Keep the frozen salmon tightly wrapped in the freezer until the last moment, and chill the serving plate in the freezer for 15 minutes.
⏲ 15 min
Take the salmon out and leave it 5 minutes, until the surface gives just enough for a knife. The inside should still be frozen.
⏲ 5 min
With a heavy, sharp knife, slice across the grain 3-4mm thick. If the blade skids, draw it back and forth rather than pressing down.
Lay the daikon and shiso on the cold plate and overlap the slices on top. Serve at once with the soy sauce and wasabi, and eat it within a few minutes, before it thaws.

Tips & Variations

Variations

Ruibe-zuke: the frozen salmon tossed in a soy marinade with salmon roe. The seasoning stays on the surface and the inside stays frozen.
Other fish: herring or squid are used too. Squid, with little fat, is harder when frozen and wants slicing thinner.
The original way: ko.wikipedia describes seafood frozen outdoors. A Hokkaido winter was the freezer.

Tips

It does what yukhoe and carpaccio forbid, all the way. Yukhoe half-freezes and says why not further: "Frozen and thawed, the cells rupture and it weeps." Carpaccio agrees: "Do not freeze it through, though — lean beef frozen solid and thawed ruptures and weeps". Ruibe freezes through. What it leaves out is the thaw.
The damage shows at the thaw, not at the freeze. Freezing and thawing explains that ice crystals tear cells and says when that shows: "On thawing, moisture escapes through those holes: dry food sitting in a puddle." The water leaves as the ice melts. Ruibe goes into the mouth still frozen, so that moment never comes. That is why the plate is chilled, the slices go out as soon as they are cut, and it is eaten within minutes. Left to thaw on the plate, it becomes exactly what those two pages warn about.
The freezing is also the safety. The same guide notes that Dutch law requires raw haring to be blast-frozen before it may be sold, and gives the reason in a line — "before it may be sold raw, because of parasites." River salmon can carry parasites too. In ruibe the freeze serves the knife and does that job as well, which is why the freezing conditions are the first step. A home freezer at −18°C may not be enough; salmon already frozen for eating raw is the sure route.
Give it five minutes before slicing. Press a knife into a hard-frozen block and the blade skids or the flesh shatters. With the surface just softened it has the firmness of yukhoe's half-freeze — except here that firmness goes all the way through.
Soy sauce only as you eat. Frozen flesh does not take it up; it only coats the surface. Dip just before each mouthful.