Take cleaned prawns in a bowl, make four small slashes from head to tail so the prawns dont curl. Now add soy sauce, fish sauce, vinegar over it and mix well. Leave to marinate for 15 mins.
Now mix flour, cornflour, salt, baking powder with water to form a liquidy paste.
Place panko in a plate and set aside.
Heat oil for deep frying.
Take prawn, dip it in the batter, coat it in breadcrumbs and deep fry in oil for 1 to 2 mins on medium high heat.