Tazuna-Zushi and Oshi-Zushi — Pressed Sushi Forms

Ingredients

• For the sushi rice
• 500 g Japanese short-grain rice, cooked and seasoned with sushi vinegar dressing
• 80 ml rice vinegar, combined with sugar and salt for sushi dressing
• 20 g caster sugar, dissolved into vinegar dressing
• 8 g fine salt, dissolved into vinegar dressing
• For oshi-zushi (battera)
• 2 mackerel fillets (saba), pin-boned, skin on, for shimesaba preparation
• 30 g coarse salt, for salting mackerel before vinegar cure
• 200 ml rice vinegar, for 2-day shimesaba marinade
• 1 sheet kombu (kelp), cut to fit oshibako surface; placed between fish and rice
• For tazuna-zushi
• 80 g smoked salmon, sliced thinly on the diagonal into long strips
• 2 eggs, made into a thin tamagoyaki sheet, sliced into diagonal strips
• 1 cucumber, sliced thinly on the diagonal into long strips
• 1 red pepper, roasted, peeled, and sliced into thin diagonal strips
• 60 g white radish (daikon), sliced thinly on the diagonal into long strips

Method

1. 1
   Two days before serving, prepare the shimesaba. Salt the mackerel fillets liberally on both sides with coarse salt and refrigerate for one hour. Rinse, pat dry, and submerge in rice vinegar for 24–48 hours, refrigerated. The flesh is ready when it has turned opaque throughout and firm to the touch.
2. 2
   Cook the short-grain rice by the absorption method. While still hot, fold in the combined vinegar, sugar, and salt dressing using a cutting motion — never stirring — and fan simultaneously to cool. Allow the rice to reach body temperature before pressing. This is where the dish lives or dies: rice used hot will volatilise its vinegar and compress into a mushy block; rice at the correct temperature — warm to the palm, neither hot nor cold — will hold a firm, cohesive shape without stodginess.
3. 3
   Soak the wooden oshibako in cold water for at least ten minutes before assembly. A dry box will bond to the rice and tear the surface on unmoulding. Shake off excess water but do not dry.
4. 4
   For battera oshi-zushi: lay the shimesaba skin-side down across the base of the moistened oshibako, trimming to fit neatly. Place the kombu sheet directly over the fish. Pack the body-temperature sushi rice firmly on top to fill the box. Apply the lid and press down with sustained, even weight — rest under pressure for 20 minutes. The rice is set when it springs back only slightly, not fully, when the pressure is briefly released.
5. 5
   Unmould the block onto a board. Using a knife wetted with water or diluted vinegar, cut into eight equal rectangles with a single, decisive downward stroke per cut — do not saw. A clean cross-section with no torn rice indicates correct moisture on the blade and correct density in the press.
6. 6
   For tazuna-zushi: lay a sheet of plastic wrap on a flat surface. Arrange alternating diagonal strips of smoked salmon (pink), egg sheet (yellow), cucumber (green), red pepper, and white radish in a repeating braid sequence across the wrap, overlapping each strip at a consistent angle. Spread a layer of sushi rice evenly over the strips. Using the plastic wrap, roll into a compact cylinder and press firmly along its length, applying even pressure with both hands. Rest for 20 minutes under slight pressure. Slice into eight rounds with a wetted knife. The cross-section should reveal a continuous, kaleidoscopic braid of colour with no gaps between ingredients.
7. 7
   Allow both forms a brief rest of five to ten minutes after cutting. The rice settles and the slices become easier to lift cleanly from the board.