For the beef, prepare the fillet by flattening it with a meat mallet or rolling pin, or cut it in half horizontally. Cut into wafer-thin slices.
For the wasabi mayonnaise, mix all of the wasabi mayonnaise ingredients together in a small bowl. Set aside.
For the spicy coating, mix all of the coating ingredients together on a plate. Roll the beef slices in the spice mix, then shake off any excess.
Heat a wok until smoking and add the groundnut oil, then add the beef and stir-fry for one minute, or until browned. Add the rice wine and season with the soy sauce and a pinch of salt. Remove from the heat and stir in the coriander and spring onion.
To serve, wrap the spicy beef in the tortillas and top with the wasabi mayonnaise. Serve immediately.