In a bowl, combine all the ingredients. Set aside.
Preheat the oil in the deep fryer to 350°F (180°C). Line a baking sheet with paper towels or top with a wire rack.
In a large bowl, combine the mirin, soy sauce, vinegar, sesame seeds, sesame oil, wasabi and pepper. Add the flour, starch and water and stir to combine. Let rest for about 10 minutes.
Place the chicken in the bowl with the batter and coat thoroughly. Fry the chicken, 4 to 5 pieces at a time, about 4 minutes or until golden brown and cooked through. Watch out for splattering. Drain on the prepared baking sheet and keep warm. Repeat with the remaining chicken.
Serve with the wasabi mayonnaise.
For crispier chicken, fry all the pieces twice.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.