Using a microplane grater, grate the knob of ginger until it has been reduced to pulp. Scoop up the pulp into a fine mesh sieve. Hold the sieve over a bowl and press on the solids with the back of a spoon. Extract as much of the ginger juice as possible, rolling the pulp back onto itself and pressing. Discard the solids. You should have about 2-3 teaspoons of juice. Divide the juice into two small bowls. One is for the hoisin-lime sauce, the other is for the asian vinaigrette.
for the asian vinaigrette
Combine 3 tablespoons grapeseed oil, 1 teaspoon ginger juice, lime zest and juice from one whole lime, honey, garlic, vinegar, wasabi powder, 1/2 teaspoon salt and pepper into a small bowl. Whisk to combine. Taste for seasonings, adjust if necessary and set aside.
for the hoisin-lime sauce
In a small bowl combine remaining 2 tablespoons grapeseed oil, garlic, remaining ginger juice, hoisin sauce, lime juice and remaining kosher salt. Whisk to combine - sauce will be thick and creamy. Taste for seasonings and adjust if necessary.
for the salad:
In a large bowl combine the scallions, bell pepper, carrot, orange segments, cilantro and mint leaves. Toss to combine. Add the chicken and toss to combine. Add the cashews and spoon 2-3 tablespoons of asian vinaigrette over the salad and toss well to coat. You can add more dressing if necessary, but don't overdress the salad.
Divide arugula onto four plates. Top the arugula with mounds of the chicken salad. Drizzle scant amount of hoisin lime sauce over the salad and dot along the rim of the plate. Sprinkle the salad with additional cashews, chow mien or rice noodles and black sesame seeds, if desired. Enjoy.