Heat the oven to 425°F and oil an oven-safe rack over a foil-lined rimmed pan. Pat wings dry and toss with baking powder and salt.
Arrange wings with gaps and bake for 25 minutes. Turn and bake for 25 to 30 minutes more until crisp and at least 165°F.
Whisk soy sauce, mirin, sugar, water, ginger, garlic and cornstarch in a small saucepan. Simmer for 2 to 3 minutes until lightly thickened.
Brush a thin coating of sauce over the cooked wings and bake for 2 to 3 minutes more until tacky.
Sprinkle with sesame seeds, rest for 3 minutes and serve as 4 appetizer portions.