In a small bowl, whisk together soy sauce, wasabi, mirin, rice wine vinegar and canola oil.† Set aside while you prepare the tuna tartare.
In a medium bowl, combine shallots, mayonnaise, honey, chili paste, sesame oil, soy sauce and wasabi, and stir well to combine. Gently fold in tuna, the avocado cubes, and cucumber and season with salt and pepper. Refrigerate while you prepare the plates.
In a medium bowl, toss the mizuna with the vinaigrette to coat. Divide the greens between 4 plates and place 1 avocado slice on each plate. Divide the tuna tartare between the 4 plates, atop the mizuna greens. Garnish each plate with green onions and sesame seeds and serve immediately.
Yield: 4 servings