Wash and dry the lettuce leaves and set them aside on a platter. Prepare all the garnishes.
10 – 15 minutes before you want to eat, heat about 1 tablespoon of oil in a large non-stick frying pan break up and fry the meat until cooked and caramelized on the edges. Set aside in a dish.
In the same frying pan, heat a teaspoon of sesame oil (optional) and a splash of neutral oil and add the onions, diced pepper, carrot, garlic, ginger and chilli and fry for a few minutes until softened. If this starts sticking to the pan, add some of the mushroom stock to prevent this.
Add the meat back to the pan along with any juices that may have seeped out. Add the oyster and hoisin sauce and stir fry along with any leftover stock and cook for a minute or 2. Add the water chestnuts and cook until the liquid has evarpourated and you have a dryish sticky mix.
Serve in the lettuce leaves and add the garnishes of your choice.