Marinate the prawns in vinegar, salt, black pepper, crushed red chilies for about 15 minutes.
Now add the cornflour and toss well.
Heat oil in a wok add the prawns and fry till golden.
Now remove on a kitchen towel and drain.
Remove excess oil from the pan leaving only 1 tsp of oil.
Place it back on the fire and add the garlic, green chilies salt pepper.
Add the prawns and stir fry for a few second then add a dash of soya sauce.
Add sugar and season according to taste.
Serve hot on a bed of chopped green onions.