Combine the cornstarch, flour, salt, black pepper, and cayenne pepper in a bowl.
In a separate bowl, beat the egg.
Dip the chicken pieces into the egg mixture, then coat them with the cornstarch mixture.
Heat the oil in a deep skillet or wok over medium-high heat.
Once the oil is hot, add the chicken pieces in batches and fry until they’re golden brown and crispy. This should take about 3-5 minutes.
Drain the chicken on a paper towel-lined plate and set aside.
In a separate pan, heat some oil and add the green onions, garlic, and ginger. Cook for a minute or two until fragrant.
In a bowl, whisk together the soy sauce, water, sugar, and cornstarch until smooth.
Add the soy sauce mixture to the pan and cook until it thickens.
Add the chili flakes and cook for another minute.
Add the fried chicken to the pan and toss to coat with the sauce.
Serve hot and enjoy!