Preheat oven to 180ºC (355ºF). Heat a small non-stick frying pan over high heat. Add half the sesame oil, vegetable oil, chilli, ginger, green onion and mushroom and cook for 2–3 minutes or until mushroom is golden. Pour over half the beaten egg and stir gently for 1 minute. Reduce the heat to low and cook, without stirring, for 5 minutes. Place the omelette in the oven and cook for 3 minutes or until omelette just sets. Set aside and keep warm. Repeat with remaining ingredients. To serve, cut each omelette in half, place on serving plates and drizzle with oyster sauce. Serves 4.