Marinate the washed chicken pieces with salt, red chili powder, black pepper powder, 2 Tablespoons of soy sauce, vinegar, ginger garlic and green chili paste.
Mix well and let it rest for at least 1 hour.
In a mixing bowl, add the remaining soy sauce, ketchup, chili sauce and oyster sauce. Mix with a spoon.
In another bowl add 1 Tablespoon of cornflour and 3 Tablespoons of water. Mix very well and add this to the sauce mixture along with chopped green chilies. Mix well and let it rest for 20 minutes.
Add the remaining cornflour and an egg into the marinated chicken. Mix well with your hand.
Heat 2 cups of oil in a kadai / wok.
Gently drop the chicken pieces into the hot oil. Do not over crowd the pan. At a time 7-8 will be good.
Fry them for 3-4 minutes. Fry rest of them in the same way.
Take them out in a tissue paper to absorb excess oil.
For the gravy, heat 2 Tablespoons of oil (in which we have fried the chicken) in another pan.
Saute chopped garlic for few seconds.
Then add white part of green onion and fry for few seconds.
Next add onion and capsicums. Fry on high flame for 2 minutes.
Then add the sauce and cornflour mixture. Mix well for 2-3 minutes.
Add 4-5 Tablespoons of hot water and cook for a minute.
After that add the fried chicken and mix for a minute.
Sprinkle some salt and pinch of sugar for the seasoning. Mix well.
Lastly add sesame oil and chopped green onion, mix well and turn off the heat.