Heat a heavy skillet or cast-iron pan over high heat until smoking hot. Add 2 tbsp neutral oil and swirl to coat. Place the tuna steak in the pan and sear 45–60 seconds on the first side without moving, until a deep brown crust forms. Flip and sear the second side 30–45 seconds for rare (internal temp ~110–115°F / 43–46°C). Remove from pan and transfer to a cutting board. Let rest 3–4 minutes before slicing thinly across the grain into 1/4-inch slices.

Cilantro-Ginger Dressing

Blend dressing

In a blender or food processor combine cilantro (leaves and tender stems), chopped fresh ginger, garlic clove, rice wine vinegar, low-sodium soy sauce, sesame oil, honey, neutral oil, lime juice, salt, and pepper. Blend until smooth and emulsified, about 30–45 seconds. Taste and adjust seasoning—add more vinegar for acidity, honey for sweetness, or salt to balance. If too thick, thin with 1–2 tsp water or more neutral oil to reach pourable consistency.

Salad Assembly

Prepare produce

Peel and dice the mango into 1/2-inch pieces (about 1 cup). Halve, pit and slice the avocado into 1/2-inch slices; toss gently with a tiny pinch of salt and a few drops of lime juice to prevent browning. Thinly slice cucumber and green onions; shred carrots if not pre-shredded. Rinse and spin-dry salad greens and roughly chop cilantro leaves if large.

Build the salad

In a large bowl or on individual plates arrange the mixed salad greens as a base. Scatter cucumber, shredded carrot, mango, avocado slices, green onion, and most of the cilantro over the greens. Reserve a small handful of cilantro for garnish.

Dress and toss

Drizzle about half the cilantro-ginger dressing over the salad (you can add more to taste). Gently toss just to coat the greens and distribute fruit and vegetables evenly. Taste and add more dressing if desired.

Top with tuna and crunch

Fan the seared tuna slices over the dressed salad. Sprinkle chopped roasted peanuts, crispy gyoza/wonton strips, and toasted sesame seeds over the top. Garnish with remaining cilantro leaves and lime wedges on the side.

Serve

Serve immediately so the gyoza strips remain crunchy and the tuna is still slightly warm and rare in the center. Offer additional dressing and lime wedges at the table.