Wash the prawns well and boil them in hot water. The way I boil prawns is simple. I boil a lot of water and put the prawns in it and reduce the heat, cover it and cook it for about 6 minutes till they start floating on top and turn white and opaque in color. Mid way, add some salt to it so that it gets absorbed in the prawns.
Drain from water and keep aside.
In a wok or pan, heat butter while heating add a couple of drops of oil to it to prevent burning.
Add the garlic to it and roast for one minute. After one minute add the curry leaves and smell the lovely aroma.
Add turmeric, pepper to it and mix. Now add the soya and vinegar to it.
Add the prawns at this stage and sautee for about 2-3 minutes
Serve hot.