Add the raw prawns, ginger, garlic, soy sauce, sugar, chilli paste, egg white and chilli oil and castor sugar to a food processor and blitz until it forms a paste, about 30 seconds.
Add the mixture to a bowl and add the cornflour, chilli oil, spring onion, salt and pepper. Mix everything until combined.
Remove the crust from the bread. Divide the prawn mixture into 4 equal portions and spread each portion onto the bread.
Place the sesame seeds in a flat plate, spreading them evenly. Press the bread into the sesame seeds, prawn side down. Ensure the bread is evenly coated.
Cut the bread into 4 triangles. Place on a platter until ready to fry.
Heat the oil in a pan or a wok, on medium to high heat. Test the oil by placing a small piece of bread into the oil. If it sizzles then you know the oil is hot enough.
Fry the triangles in batches, paste side down. It will take about 2 minutes for the prawn side and about 1 minute on the other side. The bread should be golden brown and crisp and the prawn must be cooked through.
Place the fried toast on a platter lined with paper towels, to soak up any excess oil.
Sprinkle more spring onion on top and serve with sweet chilli sauce.