Pour boiling water over noodles, drain, rinse and set aside.
Heat oil in a hot wok and fry onion until soft. Add noodles and cook for 2 minutes. Add bean sprouts, potato, tomato, tomato sauce, chilli sauce, shrimp and bean curd cake and cook over high heat, stirring, until well mixed. Add salt and sugar to taste.
Tilt wok, push noodles to one side, pour in egg, cover with noodle