Add salt to the prawns, mix well, and marinate for 10 minutes.
In a bowl, mix potato starch, baking powder, water, and egg white. Slowly add the oil in batches while stirring, until the batter becomes thick and smooth, like yoghurt.
Hold each prawn by the tail and coat the meat fully in the batter.
Heat oil to 200°C. Hold the prawn tail and place the prawn meat into the hot oil first to set the shape. When you feel it starting to float, let go. The batter will form a light bubble coating around the prawn.
Don’t fry too many at once, or they may stick together. Turn them occasionally so they colour evenly. Fry each prawn for about 2 minutes, or until golden, then take them out.
Raise the oil temperature back to 200°C and fry all the prawns again for about 20 seconds. This makes them extra crispy.
Pour out the oil. Add sugar, orange juice, and rice vinegar to the wok. Bring to a boil, then add corn starch slurry. Cook until the glaze thickens and bubbles. Turn off the heat and drizzle the glaze over the prawns.
