Wash the chicken thoroughly and pat it dry using paper towels. Cut it into small, bite-sized cubes to ensure even cooking.

In a medium-sized mixing bowl, combine cornstarch, all-purpose flour, ginger garlic paste, salt, and black pepper powder. Stir until well blended.

Add the cubed chicken pieces to the bowl and toss them in the flour mixture until evenly coated.

In a pan, heat a generous amount of oil over high heat. Once hot, drop half of the chicken pieces carefully into the oil. Fry until crisp and golden brown, about 5-7 minutes. Drain on paper towels and set aside.

Repeat the frying process with the remaining chicken pieces, ensuring they are also crispy and golden. Drain and set aside.

In a wok, heat 3 tablespoons of oil over high heat. Add chopped garlic and green chilies. Stir-fry for about 3-4 seconds until fragrant.

Toss in the onion and bell peppers, cooking for about 1 minute until slightly softened but still crunchy.

Add dark soy sauce, sweet chili sauce, red chili paste, tomato ketchup, rice vinegar, salt, and black pepper to the vegetables. Mix everything together.

In a small bowl, mix the cornstarch with 1 cup of water to create a slurry. Pour this mixture into the wok, stirring continuously. Cook for about 1 minute until the sauce thickens.

Gently fold the crispy fried chicken and cubed mango pieces into the sauce, mixing until well combined and heated through.

Sprinkle chopped spring onion greens on top for a fresh finish. Serve immediately.