Katsuo no Tataki Searing and Ice-Shock Technique

Ingredients

• 600 g bonito (katsuo), sashimi-grade; spring hatsu-gatsuo for lean flesh, autumn modori-gatsuo for richer; skin on, cleaned and filleted into a block
• 1 tsp fine sea salt, for surface seasoning before searing
• For the ice-shock bath
• 2 litres water, iced, with sufficient ice to keep below 4 °C throughout
• 1 tbsp fine sea salt, dissolved into the ice water before shocking
• For the condiments
• 80 ml ponzu, ready-made or yuzu-soy; the canonical sauce
• 4 cloves garlic, sliced 1 mm thin; Kochi-style addition
• 20 g spring onion, finely sliced
• 15 g fresh ginger, finely grated
• 2 stems myoga, finely sliced
• 8 leaves shiso (perilla), whole or chiffonade

Method

1. 1
   Prepare the ice-shock bath. Dissolve the salt in 2 litres of heavily iced water in a wide bowl deep enough to submerge the bonito block. Keep the bath beside the heat source, within immediate reach. The bath is ready when the salt is fully dissolved and the water is visibly cold, with ice floating throughout.
2. 2
   Pat the bonito block dry. Season lightly on all surfaces with fine sea salt. If using rice straw or pine needles, arrange them in a heatproof vessel and ignite, allowing the flame to reach maximum intensity before proceeding. If using a gas burner, bring it to full heat. The fire is ready when it is at its most aggressive.
3. 3
   This is where the dish lives or dies. Hold the bonito block (using tongs or a skewer) directly in or directly above the highest point of the flame, rotating it continuously so that all four long sides and both ends receive equal exposure. Sear each surface until the exterior shows an opaque, lightly charred crust of 3–4 mm depth — no more. The interior must remain completely raw and cool. Over rice straw, the characteristic smoke will adhere to the crust; over gas, rotate the block toward the flame to approximate 360-degree exposure. The seared surface is done when it is firm to the touch and shows an even pale-brown exterior with visible char at the edges.
4. 4
   Transfer the seared block immediately into the salted ice bath. Submerge it fully and hold it beneath the surface for 20–30 seconds. The shock arrests residual cooking and simultaneously firms and seasons the crust. The block is ready to remove when the exterior surface feels cool and distinctly contracted against the still-raw interior.
5. 5
   Remove the block from the ice bath and pat dry thoroughly with clean cloth or paper. Slice immediately before service into pieces of approximately 1 cm thickness. Cut surfaces oxidise to grey-brown within minutes; the fish must arrive at the table showing the clean contrast of the seared brown exterior against the red-pink interior.
6. 6
   Arrange the sliced tataki on the serving plate. In the Kochi style, lay the thin-sliced garlic beneath each piece so that the guest lifts the tataki to reveal the arrangement below. Place spring onion, grated ginger, myoga, and shiso alongside. Serve the ponzu in a separate vessel. The plate is complete when the seared and raw colours are clearly visible in each slice and the condiments are distributed without obscuring the fish.