Line two baking sheets with parchment paper and place a wire rack on top of each. Spray the racks with nonstick spray.
Place wings in a large bowl and thoroughly dry with paper towels.
Mix baking powder, cornstarch, and salt together in a small bowl.
Sprinkle the baking powder mixture evenly over the wings and toss to coat.
Evenly place on the racks and chill for at least 1 hour and up to 12.
Preheat oven to 425 degrees.
Bake the wings for 30 minutes. Flip the wings, and continue to bake until they are crisp and golden brown about 15 minutes.
When the wings have about 20 minutes left to bake, make the sauce.
Combine the sauce ingredients in a small saucepan.
Cook over medium heat, stirring often, until reduced to about ⅓ cup and thickened, about 12 minutes, cover to keep warm.
Place the wings in a large bowl, pour the sauce over them and toss to coat.
Garnish with toasted sesame seeds and thinly sliced green onions and serve immediately!