Prepare the Tuna: Sear the tuna block over high heat for 30–45 seconds per side. Plunge into an ice bath, pat dry, and slice against the grain into 1/4-inch slices. Set aside.
Emulsify the Dressing: In a small bowl, whisk together the soy sauce, rice vinegar, grated ginger, and honey. Slowly stream in the neutral oil and sesame oil while whisking vigorously until the dressing thickens and emulsifies.
Prep the Greens: Drain the red onions from the ice bath and pat dry. In a large mixing bowl, gently toss the mixed greens, edamame, and red onions with exactly half of the dressing.
Plating: Divide the dressed greens between two wide, shallow bowls. Fan the sliced avocado on one side. Shingle the slices of Tuna Tataki gracefully over the top of the greens.
Garnish: Drizzle the remaining Wafu dressing directly over the tuna slices. Finish with a sprinkle of toasted sesame seeds.