Place the boneless chicken cubes in a large bowl and add salt, black pepper, ginger garlic paste, dark soy sauce, egg, flour, and cornstarch in quantities specified above.
Mix all these ingredients with the chicken properly until the chicken is completely coated and allow it to marinate for 25-30 minutes.
Once marinated, place a fryer or a deep pot over the stove and bring it to medium-high heat.
Fry the marinated chicken pieces in the oil for 5-6 minutes or until they turn golden brown and crispy.
Set the fried chicken aside and prepare for the sauce.
In a bowl add water, soy sauce, chili sauce, tomato ketchup, white vinegar, and cornstarch and mix it well, and set aside.
Heat a pan on medium heat and add 2 tbsp of cooking oil. Add minced garlic and ginger and fry it until it turns golden brown.
Next, add green chilies, onions, and bell pepper to the pan and sauté for 2 minutes.
Add salt, pepper, and sugar to the pan and mix it up until it dissolves.
Mix and add the sauce you prepared and set aside and cook until the sauce is thickened.
Finally, add the crispy chicken and mix it all up for 1-2 minutes and garnish it with green onions.