Keep the fish well-chilled until ready. Using a very sharp long-bladed knife, trim away any bloodline or sinew from the tuna. Pat dry with paper towels.

Slice the tuna into very thin sashimi slices (about 1/8 inch / 3 mm thick). For presentation, cut approximately 12 ounces into 12–16 slices depending on preferred portion size.

Arrange slices on a chilled plate in a single layer or slightly overlapping, leaving space for garnishes.

Thinly slice the jalapeño into rounds. If you prefer less heat, remove seeds and membranes before slicing. Reserve a few very thin slices for placing atop some tuna pieces as decorative heat points.

Scatter microgreens or cilantro lightly over the plate and sprinkle the toasted sesame seeds and sliced scallion evenly on top of the tuna.

Brush or squeeze a few drops of fresh lime juice over the fish just before serving to brighten flavors.

Ponzu & Seasoning

Make ponzu dressing

In a small bowl, combine 3 tbs ponzu sauce, 1 tsp light soy sauce, 1 tsp rice vinegar, 1 tsp mirin, 1/2 tsp toasted sesame oil, and 1/2 tsp freshly grated ginger. Whisk briefly to emulsify. Taste and adjust balance — add up to 1 tsp more ponzu for acidity/salt if desired.

Season the dressing with 1/4 tsp kosher salt and 1/8 tsp freshly ground black pepper; whisk again until salt dissolves.

Drizzle the ponzu dressing over the arranged tuna slices sparingly (about 1/2 to 1 tbs per portion), or serve the dressing on the side for dipping.

Top a few slices of tuna with the reserved jalapeño rounds so diners get bursts of heat. Serve immediately so the fish stays cool and textures remain pristine.