Heat the oil in a wok and stir-fry the carrot and mushrooms for 2 mins until just starting to soften. Add the beansprouts, onions, ginger and garlic and stir-fry for another 1-2 mins or until the beansprouts are starting to turn transparent. Season with the soy sauce and set aside. Can be made up to 4 hrs ahead.
Heat a medium frying pan, add a little oil, then tip out the excess. Pour in a little of the egg and swirl around the pan to make a thin, even layer. Fry for 30 secs or until the edges turn golden, then flip over with a palette knife for another 10 secs. Slide out onto greaseproof paper and repeat until you have made six pancakes. Can be made up to a day ahead.
Cut each pancake in half. Spoon a little of the veg mix in the centre of the half-moon of pancake and roll up, tucking in the edges. Steam briefly to heat the rolls just before serving or microwave on High for 30 secs.