Masu-zushi (鱒寿司, Toyama pressed trout)

Ingredients

Equipment Needed

• •Round masu-zushi box or round oshibako, or an 18cm round cake pan with a flat plate
• •Hangiri (wooden sushi rice tub), or a wide nonreactive bowl
• •Rice paddle (shamoji)
• •Clean cotton kitchen string
• •Small weight, about 1 to 1.5kg
• •Rice cooker or heavy saucepan

Instructions

1. 1

   Choose the trout

   Buy sakuramasu in spring if you can find it, or use ocean trout sold specifically for raw eating and freezer-treated for parasite control. Keep it cold while you work. This dish has no sauce to hide behind, and no salt-vinegar cure will make doubtful fish suitable for raw eating.

   Ask the fishmonger plainly: would you eat this raw today, and has it been frozen for parasite control? A useful answer is worth more than a pretty label.
2. 2

   Salt the trout

   Lay the trout on a tray and sprinkle it evenly with the curing salt. Refrigerate for 30 minutes, until beads of moisture gather on the surface. Salt pulls out excess water and firms the flesh, so the fish will sit cleanly on the rice instead of weeping into it.

3. 3

   Vinegar cure

   Rinse the salt off quickly under cold water, pat the trout very dry, and set it in a shallow dish. Pour over the 120ml rice vinegar and turn once. Cure 15 to 25 minutes, depending on thickness, just until the surface looks slightly paler and firmer. Too long in vinegar makes the outside chalky, and chalk is not a seasoning.

4. 4

   Slice the fish

   Pat the cured trout dry again and slice it into broad sheets, about 3 to 4mm thick, drawing the knife through in one clean pull. Sawing bruises the face of the fish and makes the finished round look muddy. Let the knife do the seasoning.

5. 5

   Cook the rice

   Rinse the rice in several changes of water until the water runs almost clear, then drain it for 20 minutes. Cook with the measured 330ml water in a rice cooker, or in a heavy saucepan brought to a boil, covered, lowered to the faintest heat for 12 minutes, then rested off the heat for 10 minutes. Rinsing removes loose starch; draining lets the grain take water evenly.

6. 6

   Season the rice

   Warm the 80ml rice vinegar with the sugar and 1 1/2 teaspoons salt just until dissolved, then take it off the heat. Turn the hot rice into a hangiri, or a wide nonreactive bowl, and sprinkle the seasoned vinegar over it. Fold with a rice paddle while fanning until the grains are glossy and body-warm. Hot rice drinks the vinegar; mashed rice becomes paste.

7. 7

   Soften the leaves

   Cover the bamboo leaves with hot water for 5 minutes, then rinse, wipe, and pat them dry. This makes them pliable enough to fold without tearing and clears away storage dust. The leaves should lend a green fragrance, not grit.

8. 8

   Build the round

   Line an 18cm round masu-zushi box, oshibako, or cake pan with bamboo leaves, shiny side toward the food and tips hanging over the edge. Lay the trout slices in a slightly overlapping circle, best face down if you plan to turn the sushi out. Fill small gaps with trimmings. With hands dampened in vinegar water, spread the body-warm rice over the fish in an even layer, pressing only enough to level it.

   Body-warm rice is the quiet trick. Hot rice toughens the fish; cold rice will not settle into the press.
9. 9

   Press gently

   Fold the leaves over the rice, set on the flat lid or a plate, and add a 1 to 1.5kg weight. Refrigerate 4 to 6 hours. The weight should persuade, not punish. You want the layers joined, the round firm, and the rice grains still visible.

10. 10

    Cut with string

    Let the wrapped sushi stand at cool room temperature for 20 minutes before cutting, so the rice softens slightly. Unfold the leaves and turn the round fish-side up if needed. Slide a clean cotton string under the round, bring the ends up over the top, cross them, and pull outward until the string cuts through. Repeat to make 8 wedges. Serve with a little gari if you like, but no heavy sauce. The fish and vinegar have already spoken.

Chef Tips

• •Sakuramasu in spring is the Toyama ideal. Ocean trout or salmon sold for raw eating is a sensible home stand-in, but say plainly what it is. The method stays honest that way.
• •Bamboo leaves matter. Parchment will help you press the shape, but it will not give the faint green scent that belongs to masu-zushi. Use parchment only when the leaves are truly out of reach.
• •Keep the press light. If the rice layer comes out dense and gummy, the weight was too heavy or the rice was mashed during shaping. Pressed sushi should hold together without losing the life of the grain.
• •Use string for the first cuts. A sharp damp knife works in a pinch, wiped after every slice, but string moves through fish and rice without dragging one layer into the other.

Advance Preparation

• •The bamboo leaves can be softened, wiped dry, and stored wrapped in a clean towel one day ahead.
• •The seasoned vinegar for the rice can be made up to a week ahead and kept covered at room temperature.
• •Finished masu-zushi is best pressed 4 to 6 hours and eaten the same day. Keep it refrigerated because the fish is cured but still raw, then let it stand 20 minutes before cutting.
• •Do not press it for more than 24 hours. The rice hardens and the vinegar keeps tightening the fish.

Frequently Asked Questions

Nutrition Information

1 serving (about 265g)