To marinate the chicken: Wash the chicken and cut it into small pieces. In a bowl, add the chicken pieces, cornstarch, all-purpose flour, 1 tablespoon soy sauce, 1/2 tablespoon black pepper powder, 1 tablespoon red chili powder, and crack in the egg. Mix everything well, cover, and let it rest for 30 minutes.

For the cornstarch slurry: In a bowl, add 1/2 cup water, 1 tablespoon soy sauce, 2 tablespoons tomato ketchup, 1 tablespoon vinegar, 2 tablespoons red chili sauce, and 1 tablespoon cornstarch. Mix well until smooth.

Heat oil in a deep pan or wok. Add the marinated chicken pieces one by one and fry on medium heat until golden and cooked through. Fry all the chicken pieces this way.

In another pan, heat a little oil. Add the chopped garlic and green chilies, sauté for 1 minute, then add the chopped onion and bell pepper. Sauté for 1-2 minutes, making sure not to overcook the vegetables.

Add the prepared cornstarch slurry to the pan and mix well. Once it comes to a boil, add the fried chicken pieces.

Mix well so the chicken is evenly coated with the sauce. Cook for another 1-2 minutes, then turn off the heat.

Transfer to a serving plate, sprinkle with chopped cilantro or green onion tops and sesame seeds, and serve hot.