Combine the minced chicken, oyster sauce and pepper in a bowl. Heat oil in a wok and fry garlic until beginning to brown. Add the chicken and stirfry over high heat until mixture loses its pinkness. Add mushrooms and continue frying until wilted - about 3 minutes.
Add the sauce mixture and bring to the boil - the sauce will thicken slightly. Take wok off the heat.
Beat eggs, water and salt together. Heat a tea¬spoon of oil in a small, * preferably nonstick frying pan. Pour in enough egg to coat the base of the pan thinly and cook one side until golden brown. Flip and cook the other side of a minute. Transfer to a plate and make more omelettes this way until egg is used up.
To serve, place 2 - 3 tbsp of filling in the centre of each omelette and roll to enclose (allowing a little filling to 'spill' out at the edges). Place on serving plate and top with the relish (see below). Garnish with sprigs of fresh coriander if wished. Serve hot with plain boiled rice or thick slices of crusty bread.
Just before serving, combine the cucumber, carrot, onion and chilli. Add vinegar, salt and sugar and toss to combine. Place over the omelettes but leave the juices behind.
* small omelettes 12 - 14 cm across look better than large ones