Cut the tofu lengthwise into 4 slices. Place the slices on several layers of paper towels; cover with additional paper towels. Let stand 5 minutes. Cut each slice diagonally into 2 triangles. Place the tofu in a shallow baking dish. Combine the sherry, soy sauce, and sesame oil in a small bowl. Pour over tofu, and refrigerate 20 minutes.
Preheat oven to 450°.
Bake at 450° for 25 minutes. Cool to room temperature; chill 30 minutes.
Combine the greens, cucumber, and onions. Combine the juice and remaining ingredients; stir with a whisk. Drizzle juice mixture over greens, and toss well to coat. Place 2 cups salad on each of 4 plates; top each portion with 2 tofu triangles.