Spread the toasted sesame seeds on a plate. Press each side of the tuna into the seeds so the exterior is evenly coated; press firmly to adhere a thin crust but do not crush the fish.

Sear tuna

Heat a heavy skillet (cast-iron preferred) over high heat until very hot. Add 1 tablespoon neutral oil and swirl to coat. When oil shimmers, place the sesame-crusted tuna in the pan and sear 25–30 seconds per side for rare (adjust 15–45 seconds depending on thickness). Sear the edges quickly for 10–15 seconds to set the crust. Remove tuna to a cutting board and let rest 2–3 minutes before slicing thinly on the bias into 1/4-inch slices.

Toasted Wontons (Crispy)

Bake or pan-fry wontons

Preheat oven to 375°F (190°C) if baking. For baked: brush both sides of wonton wrappers lightly with vegetable oil, cut into triangles if desired, arrange in a single layer on a parchment-lined baking sheet, sprinkle with fine sea salt, and bake 6–9 minutes turning once halfway, until golden and crisp. For pan-fry: heat 1–2 tablespoons oil in a skillet over medium-high, fry wontons in batches 30–60 seconds per side until blistered and crisp, drain on paper towels and salt immediately. Let cool to room temperature.

Sesame-Ginger Dressing

Whisk dressing

In a bowl or jar combine soy sauce, rice vinegar, lime juice, honey, grated ginger, minced garlic, toasted sesame oil, neutral oil, and sriracha if using. Whisk or shake until emulsified. Taste and adjust seasoning with salt or more honey/acid as needed. Stir in 1 teaspoon toasted sesame seeds.

Salad Assembly

Prepare vegetables and fruit

Toss the mixed greens, mango cubes, cucumber slices, red pepper strips, thinly sliced red onion, and cilantro (if using) in a large bowl. Gently fold in the diced avocado just before dressing to avoid browning.

Dress salad

Drizzle about two-thirds of the sesame-ginger dressing over the salad and gently toss until components are lightly coated. Reserve remaining dressing for the tuna and individual plates.

Plate and finish

Divide the dressed salad among 2 plates (or one large platter). Fan the sliced sesame-crusted tuna over the top of each salad portion. Spoon 1–2 teaspoons of reserved dressing over the tuna slices for gloss. Garnish with crispy wonton triangles tucked into the salad, a sprinkle of extra toasted sesame seeds, and sliced scallions. Serve with lime wedges on the side.

Timing & Serving Notes

For best results, sear the tuna just before serving so it remains rare in the center. Wontons can be made ahead and stored in an airtight container for a day; re-crisp in a 300°F oven for 3–4 minutes if needed. Leftover dressing will keep refrigerated up to 5 days.