Heat oil in a wok.
On high flame, saute ginger garlic paste, add onions, green chilies and saute for a few seconds.
Add one shrimp at a time to the wok and stir fry on high flame until shrimp begins to curl up.
Add soya sauce, chili paste, vinegar and give a quick stir until sauces coat shrimp.
Add water, bring to a boil.
Meantime make a paste of cornstarch, salt, black pepper powder.
When water comes to a boil, pour cornstarch paste over chili shrimp gravy and stir vigorously to avoid lumps.
Let the gravy boil and thicken to desired consistency
Sprinkle green onions and serve immediately with steamed rice, fried rice or noodles.