In a mixing bowl, combine the chicken pieces, egg, 2 tablespoons of cornstarch, all-purpose flour, 1 tablespoon of soy sauce, and black pepper. Toss until evenly coated and let marinate for at least 15 minutes.
Heat 2 to 3 inches of cooking oil in a deep frying pan or wok over medium-high heat. Carefully drop the marinated chicken pieces into the hot oil in batches.
Fry the chicken for 5 to 7 minutes until golden brown and crispy. Remove with a slotted spoon and drain on paper towels.
In a separate wok or large skillet, heat 2 tablespoons of oil over medium-high heat. Add the minced ginger, garlic, and the white parts of the green onions, stirring for 1 minute until fragrant.
Stir in the tomato ketchup, 2 tablespoons of soy sauce, red chili sauce, and sugar. Allow the sauce to bubble for 30 seconds.
Pour the cornstarch slurry into the wok and stir continuously until the sauce thickens and becomes glossy.
Add the fried chicken pieces to the thickened sauce, tossing well so each piece is thoroughly coated.
Garnish with the green parts of the green onions and chopped fresh cilantro. Serve immediately.