To make the orange chicken sauce, whisk all the ingredients together in a small bowl. Set aside.

Prepare a dredging station for the chicken: In a large bowl, whisk the egg, salt, white pepper, and vegetable oil. In a second bowl, stir together the cornstarch and flour.

Dip the chicken pieces into the egg mixture. Shake off any excess and dredge the chicken in the cornstarch mixture. Press down lightly so the cornstarch adheres on all sides.

In a deep fryer or Dutch oven, heat 4 inches of vegetable oil to 350°F. Working in batches, drop the chicken pieces into the oil one at a time. Deep-fry until the breading turns golden brown and the chicken reaches an internal temperature of 165°F, about 3 to 4 minutes. Remove the chicken from the oil and transfer to a rack to drain.

When the chicken has almost finished frying, heat the sesame oil in a large skillet over medium heat. Add the dried chilis and cook until lightly toasted, about 1 minute. Add the chili flakes and cook until fragrant, about 1 minute. Add the garlic and ginger and cook until fragrant, about 1 minute. Add the reserved orange chicken sauce to the skillet and bring the mixture to a simmer. Cook, stirring, until the sugar dissolves and the sauce thickens, 1 to 2 minutes. Add the chicken to the skillet and toss to coat. Serve immediately.