Trim any sinew from the tuna and cut into 1/2-inch dice. Place tuna in a medium bowl. Dice the avocado into roughly the same size pieces and put into a small bowl with a squeeze of lime to prevent browning. Julienne the daikon and thinly slice the cucumber. Arrange mixed salad greens on a large serving platter or divide between 4 plates.

Add the drained wakame, sliced red onion, and half the scallions to the bowl with the tuna. Gently add the avocado and the julienned daikon and cucumber, taking care not to mash the avocado.

Garlic-Ginger Wasabi Dressing

Make dressing

In a small bowl or jar combine light soy sauce, rice vinegar, toasted sesame oil, neutral oil, grated ginger, minced garlic, wasabi paste, honey, and lime juice. Whisk or shake vigorously until combined and slightly emulsified. Taste and adjust: add more wasabi for heat, more honey for sweetness, or more lime for brightness.

Reserve about 1 tablespoon of the dressing for drizzling over the plated greens. Pour the remaining dressing over the tuna-avocado mixture and gently toss to coat all pieces evenly. Let marinate 2–5 minutes to allow flavors to meld (do not marinate long if you prefer firm tuna texture).

Assembly & Garnish

Divide the dressed tuna and vegetable mixture evenly over the prepared salad greens on each plate or place the entire mixture in the center of the platter on top of the greens.

Drizzle the reserved tablespoon of dressing over the greens for extra brightness. Season lightly with sea salt and freshly ground black pepper.

Sprinkle toasted sesame seeds, the remaining scallions, and toasted nori strips (if using) over the salad. Serve immediately.