01 - In a large mixing bowl, combine the chicken pieces with soy sauce, ginger-garlic paste, black pepper, salt, egg, cornstarch, and all-purpose flour. Toss until every piece is evenly coated. Allow the chicken to marinate for at least 15 minutes at room temperature.
02 - Heat oil in a deep pan or wok to 350°F. Working in batches to avoid overcrowding, carefully lower the marinated chicken pieces into the hot oil. Fry until golden brown and crisp, approximately 4-5 minutes per batch. Transfer the fried chicken to a paper towel-lined plate to drain excess oil.
03 - In a clean wok or large skillet, heat 2 tablespoons of oil over medium-high heat. Add the finely chopped garlic, ginger, and slit green chilies. Stir-fry for about 1 minute until fragrant and the aromatics release their essential oils.
04 - Add the sliced onion and diced bell peppers to the wok. Toss vigorously over high heat for 2 to 3 minutes, keeping the vegetables crisp-tender with a slight char. Avoid overcooking to maintain their vibrant color and crunch.
05 - Pour in the soy sauce, red chili sauce, tomato ketchup, vinegar, sugar, black pepper, and a pinch of salt. Stir everything together thoroughly, then add 1/2 cup of water. Bring the mixture to a simmer.
06 - Slowly pour in the cornstarch slurry while stirring continuously. Cook for another minute or two until the sauce coats the back of a spoon and reaches a glossy, thick consistency.
07 - Add the fried chicken pieces back into the wok. Toss vigorously to coat every piece evenly with the sauce. Continue stir-frying for 2 to 3 minutes so the chicken absorbs the flavors while maintaining its crunch.
08 - Transfer to a serving dish and garnish generously with chopped spring onions. Serve immediately as a standalone starter or alongside steamed rice, fried rice, or noodles.