Wash the chicken and pat it completely dry using paper towels. Cut into uniform 1-inch cubes for even cooking.

In a medium mixing bowl, combine cornstarch, all-purpose flour, ginger garlic paste, salt, and black pepper. Mix well until smooth.

Add the cubed chicken pieces to the bowl and coat them thoroughly with the flour mixture, shaking off any excess.

Heat oil for frying (about 2 inches deep) in a pan over high heat to 350°F. The oil should shimmer and sizzle when you drop in a small piece of coated chicken.

Carefully drop half of the chicken pieces in the hot oil and fry for 5 to 7 minutes until crisp and golden brown, turning occasionally for even browning.

Remove fried chicken with a slotted spoon, drain on paper towels, and keep aside. Let oil return to temperature before frying the second batch.

Fry the remaining chicken pieces until golden and crispy. Drain and set aside with the first batch.

Heat 3 tablespoons of oil in a wok over high heat until it just begins to smoke. Add garlic and green chilies and fry for 3 to 4 seconds until fragrant.

Add onion and bell peppers and cook for 1 minute, stirring constantly. They should remain crisp-tender with slight char.

Add dark soy sauce, sweet chili sauce, red chili paste, tomato ketchup, rice vinegar, salt, and black pepper to the wok and mix well.

Mix 2 tablespoons cornstarch with 1 cup water to make a slurry. Pour the slurry into the wok and stir constantly.

Cook for 1 minute or until the sauce thickens and becomes glossy, stirring constantly. Add more water if the sauce becomes too thick.

Add the fried chicken and fresh mango cubes to the wok. Toss everything together for 30 seconds to coat with sauce while keeping the chicken crispy.

Garnish with chopped green onions and serve immediately while hot for the best texture and flavor.