Heat oil in a heavy bottomed vessel, make small balls of the marinated chicken and carefully drop into the hot oil. Cook on low medium flame and towards the end of the cooking process increase flame to high and deep fry to a golden brown shade. Drain with a slotted spoon and place on absorbent paper. Keep aside. Heat a heavy bottomed vessel, add oil, add the chopped garlic and saute on high flame for about 30 secs. Add the chopped ginger and green chilies and saute for a few more secs. Add the spring onion whites and saute for 3 mts on high flame. Reduce to medium heat and add the brown sugar, soya sauce, tomato ketchup, chilli sauce and vinegar. Combine well and cook for 2 mts. Add 1/4 cup chicken stock or water and cook for a mt. Add the deep fried chicken balls and cook for 4 mts. Adjust salt, if necessary. Add the cornflour water and cook, tossing the contents, for 4-5 mts. You will find that it becomes thick due to cornflour. Add the chopped spring onion greens and combine. Garnish with more spring onion greens. Serve hot as a starter/appetizer.