Marinate chicken pieces with all the ingredients mentioned under marination and keep aside for half an hour.
Heat oil in a pan and fry marinated chicken pieces. Make sure each piece is separate after frying and the meat is cooked well. Keep the fried chicken pieces aside.
In the remaining oil, sauté roughly chopped onion, ginger, garlic, green chilli, 1/4 cup chopped spring onion and capsicum till translucent.
Add soya sauce, chilli sauce, tomato sauce, vinegar, sugar, ajinomoto (optional), food colour, salt and required quantity of water for the gravy.
Mix well and bring it to boil.
When the gravy starts boiling, mix 2 tbsp corn flour in half cup water and add it to the gravy.
When the gravy thickens, add the fried chicken pieces, mix well and remove from fire.
Garnish with chopped spring onion and serve hot with fried rice / noodles.