In a large mixing bowl, combine the cut chicken pieces with the egg, 2 tbsp soy sauce, 1 tsp sesame oil, and black pepper. Mix well to coat. Let marinate for at least 10 minutes while you prepare the sauce.

In a small saucepan, whisk together the chicken broth, 1/4 cup soy sauce, honey, rice vinegar, 1 tbsp sesame oil, ginger, garlic, and sriracha (if using). Bring the mixture to a simmer over medium heat, stirring occasionally.

In a small separate bowl, whisk together 1 tbsp cornstarch and 2 tbsp water to create a slurry. Once the sauce is simmering, slowly pour the cornstarch slurry into the saucepan while whisking constantly. Continue to whisk and simmer for 1-2 minutes until the sauce thickens to your desired consistency. Remove from heat and set aside.

In a separate medium-sized bowl, combine the 1/2 cup cornstarch, flour, baking powder, and 1/4 tsp salt. Add the marinated chicken pieces to the dry coating mixture and toss until each piece is thoroughly coated. Shake off any excess.

Preheat your air fryer to 400°F (200°C) for 5 minutes. Working in batches, place a single layer of coated chicken pieces in the air fryer basket, ensuring not to overcrowd. Lightly spray the chicken with cooking oil spray (optional, but helps with crispiness).

Air fry for 10-12 minutes, flipping the chicken pieces halfway through, until golden brown and cooked through (internal temperature reaches 165°F / 74°C). Repeat with remaining chicken batches.

Once all chicken is cooked, transfer it back into the large mixing bowl (or a clean bowl). Pour the prepared sesame sauce over the crispy chicken. Toss gently with tongs until all chicken pieces are evenly coated.

Transfer the sesame chicken to a serving platter. Garnish generously with toasted sesame seeds and sliced green onions. Serve immediately with steamed rice and a side of your favorite stir-fried vegetables.