Prepare the Prawn Mixture: In a large bowl, combine the finely chopped King prawn meat, spring onions, ginger, garlic, soy sauce, sesame oil, egg whites, and cornstarch. Mix until well combined.
Prepare the Bread: Spread the prawn mixture evenly onto one side of each slice of bread. Press down slightly to ensure the mixture adheres to the bread.
Add Sesame Seeds: Sprinkle sesame seeds over the prawn-topped bread slices, pressing them lightly into the prawn mixture.
Cut the Bread: Cut each slice of bread diagonally into triangles.
Fry the Prawn Toasts: Heat the vegetable oil in a frying pan over medium heat. Once the oil is hot, carefully place the prawn-topped bread slices into the pan, prawn side down. Fry for about 2-3 minutes until golden brown, then flip and fry the other side for an additional 1-2 minutes until the bread is crispy.
Drain and Serve: Remove the prawn toasts from the oil and place them on paper towels to drain any excess oil.
Serve: Serve the prawn toasts hot with sweet chilli sauce or soy sauce on the side for dipping.