Tuna Roll

Rinse the 180g sushi rice under cold running water for 2 minutes until water runs almost clear, then drain completely for 10 minutes. Add rice and 220ml cold cooking water to a lidded pot, bring to a rolling boil over medium-high heat, then reduce heat to the lowest setting, cover, and simmer for 15 minutes without lifting the lid (or cook in a rice cooker on standard white rice mode for 18 minutes). Once cooked, turn off heat and let rice rest covered for 5 minutes, then transfer hot rice to a wide wooden or glass bowl, gently fold in 30ml seasoned rice vinegar with a rice paddle, then fan the rice for 3 minutes to cool it to room temperature (21C/70F) — do not mash the rice grains.

Pat the 225g sashimi-grade tuna completely dry with paper towels, then slice it lengthwise into 1cm (1/2 inch) thick uniform strips, removing any dark bloodline sections. Mix 120ml cold water and 15ml rice vinegar in a small bowl to create a hand-dipping bath to prevent rice from sticking to your fingers during rolling. Arrange nori sheets, wasabi, sesame seeds, and tuna strips within easy reach of your work surface.

Place a bamboo sushi rolling mat (makisu) flat on your work surface, with the bamboo slats running horizontally. Lay one full nori sheet shiny-side down on the mat, then dip your fingers in the vinegared hand bath to prevent sticking. Spread 1/4 of the seasoned sushi rice (roughly 135g cooked rice) evenly over the bottom 2/3 of the nori sheet, leaving a 5cm (2 inch) bare strip of nori at the top edge to seal the roll. Press the rice gently into a thin, even 5mm (1/4 inch) layer — do not pack the rice tightly.

Smear a thin line of 1/4 teaspoon (1.25g) wasabi paste horizontally across the center of the rice layer, then place 1/4 of the sliced tuna strips (roughly 56g) in a single even line directly on top of the wasabi, running the full width of the nori sheet. Sprinkle 1/4 of the toasted sesame seeds (roughly 2.25g) over the rice layer for extra nuttiness, if desired.

Lift the bottom edge of the bamboo mat closest to you, folding it up and over the tuna filling to meet the top edge of the rice layer. Gently squeeze the mat along the length of the roll to form a tight, even log, pulling the mat slightly toward you to compress the roll without squeezing filling out the sides. Continue rolling upward until the bare 5cm nori strip seals the roll, dabbing a tiny bit of cold water on the nori edge if it does not stick. Press the mat firmly around the full roll for 10 seconds to set its shape.

Unroll the bamboo mat and transfer the finished log to a clean cutting board. Dip a sharp, thin-bladed knife in the vinegared hand water between every cut to prevent sticking, then slice the roll into 8 even 2.5cm (1 inch) thick pieces. Repeat the layering, rolling, and slicing process with the remaining 3 nori sheets, rice, and filling. Arrange the sliced rolls cut-side up on a serving platter, and serve immediately with extra wasabi, pickled ginger, and low-sodium soy sauce if desired.