Brush both sides of the sandwiches with the remaining egg white to give it a nice gloss, and then stick the sesame seeds onto the bread.
Halve your four remaining prawns, and push them into one side of the bread, so that they stick.
If you have your own toastie maker, then simply pop your sandwiches in it, and wait for three minutes.
Otherwise, use a frying pan and get it very hot. Use a drop of oil to stop it sticking, and then place the sandwich onto the pan.
Let it cook for two-and-a-half minutes on each side, and then serve with the sweet chilli sauce on the side.