Remove the Wagyu from the refrigerator 30–45 minutes before cooking so it comes to near room temperature. Pat dry with paper towel and trim any large exterior silver skin if present, leaving fat cap intact.

Season

Lightly press seaweed salt onto both sides of the steak just before cooking — use roughly 1 to 1.5 teaspoons total for a 1 lb steak. Do not oversalt; Wagyu's fat carries flavor.

Sear

Heat a heavy skillet or cast-iron pan over high heat until smoking. For an inch-thick steak: add 1 tsp neutral oil to the pan, place steak and sear 60–90 seconds per side to develop a deep brown crust. For thicker cuts, sear sides and render fat cap briefly (30–60 seconds) to brown. Aim for rare to medium-rare internal temperature (120–128°F / 49–53°C) — Wagyu is best served rare to medium-rare.

Rest & slice

Remove steak to a cutting board and rest 4–6 minutes. Slice thinly against the grain into bite-size pieces for tableside service. Arrange on warmed platter.

Finish with scallion oil

Just before serving, spoon 1–2 teaspoons of the warm grilled scallion oil over the sliced beef to gloss and add aroma. Garnish with the thinly sliced scallion reserved for garnish.

Grilled scallion oil

Prepare scallions and aromatics: preheat a grill pan or cast-iron skillet to medium-high. Toss the halved scallions and smashed garlic with a little of the neutral oil (reserve most oil for infusion). Grill or char the scallions and garlic until well-browned and softened, about 4–6 minutes, turning so most surfaces get char marks.

Infuse oil: transfer the charred scallions and garlic to a small saucepan with the 1/2 cup neutral oil. Warm gently over low heat for 8–10 minutes — do not boil — to extract volatile aromatics and smoky flavor. Stir occasionally.

Finish and strain: remove from heat, stir in 1 tsp light soy sauce for depth. Let steep 10 minutes. Strain through a fine-mesh sieve into a heatproof container, pressing solids to release oil. Reserve strained oil warm or at room temperature. If desired, whisk in 1 tsp neutral oil to yield a glossy finish for spooning over steak.

Spicy ponzu

Combine base liquids: in a small bowl or jar, whisk together 1/4 cup soy sauce, 2 tbsp yuzu (or 1 tbsp lemon + 1 tbsp lime), 1 tbsp mirin and 1 tsp rice vinegar until smooth.

Add heat and texture: stir in 1 tsp sambal oelek (adjust to taste) and 1/2 tsp chili oil if using. Add 1 tbsp bonito flakes for extra umami if desired.

Adjust and rest: add 1 tbsp water to mellow intensity. Let the ponzu sit 5–10 minutes to marry flavors; if using bonito, strain through a fine sieve before service or leave in for tableside visual/texture depending on preference.

Serve: transfer to a small pour bowl for tableside pouring or individual dipping ramekins for guests.