Heat the oil in a large frying pan and add the mushrooms and spring onion. Stir-fry over a medium heat for 4–5 minutes until the mushrooms have softened.
Increase the heat and add the beaten egg to the pan. Cook for a further 2 minutes, stirring frequently, until the egg is cooked. Stir in the rice and heat until it is really hot, then remove from the heat and spoon the mixture into bowls.