Heat a frying pan over a medium heat and fry the sesame seeds, onion, pepper and, if using, a pinch of chilli flakes in a little oil for a couple of minutes.
Crack the eggs into the pan and let the whites set, then break the yolks and press them so they spread out.
Lay the tortilla on top and press it gently onto the egg so it sticks, then flip it over and fry it on the tortilla side for about 3 minutes.
Drizzle soy sauce over the egg and top with a little chilli sauce and mayonnaise.*See the video above the recipe.
Fold the tortilla wrap in half, place it on a plate and top with spring onion.