Pat the pre-cooked king crab legs dry with paper towels. Using kitchen shears or a sharp chef’s knife, carefully split the shell lengthwise to expose the meat while keeping pieces intact. Cut into 6 portions suitable for placing on each tostada (about 2–3 oz meat per piece).

Season for robata grilling

Lightly brush each piece of crab meat with neutral oil (about 1 tsp total across pieces). Season very lightly with kosher salt (a light pinch per piece) and a few turns of freshly ground black pepper. Let rest 5 minutes to absorb.

Grill

Preheat a robata grill, cast-iron grill pan, or broiler to high heat (medium-high if using stovetop). Place crab pieces shell-side down and meat-side up over the heat for 1–2 minutes to warm and gently char the edges; flip and char the shell side briefly if desired (30–45 seconds). Remove and set aside. Goal: heat through, add slight char and smoky flavor without overcooking.

Sauce & Dressing

Make the spicy yuzu mayo

In a small bowl, whisk together Japanese mayonnaise (1/2 cup), sriracha (1 tbs), yuzu kosho (1/2 tsp), and rice vinegar (1 tsp) until smooth. Taste and adjust: add more sriracha for heat or more yuzu kosho for citrus-umami. Transfer to a squeeze bottle or piping bag for neat plating.

Tostadito Assembly & Crunch

Prep tostada bases

Warm mini tostada shells in the oven at 350°F (175°C) for 3–5 minutes until crisp. Place 6 shells on a serving platter.

Create crunch layer

Evenly distribute a thin layer (~1–2 tsp) of tempura crisps or crushed panko onto each tostada. Sprinkle a light pinch of furikake over the crisps to introduce umami and seaweed flavor.

Vegetables & Herbs

Prepare garnishes

Julienne cucumber and thinly slice radish. Place a small mound (about 1–2 teaspoons) of cucumber on each tostada, then arrange a couple thin radish slices on top. Scatter a few micro cilantro leaves and a pinch of sliced scallion over each.

Garnish & Finishing

Assemble final tostaditos

Place a warm charred crab piece atop the cucumber/radish bed on each tostada. Pipe or drizzle about 1 teaspoon of the spicy yuzu mayo over the crab. Drizzle 1/4 teaspoon of unagi glaze over each for a sweet-savory finish. Lightly brush a drop (a few drops total) of sesame oil across the tostaditos for aroma.

Finish and serve

Sprinkle toasted white sesame seeds and black sesame seeds over each tostadito, and a final scattering of furikake if desired. Squeeze a few drops of fresh lime over each tostada just before serving. Arrange 6 pieces on a platter and serve immediately while crab is warm and crisps are crunchy.