Heat the oil in a wok or a large skillet over a high heat. Stir fry all of the vegetables coating them with the oil. Pour in the stock, oyster sauce and soy sauce and stir until the vegetables are ?al dente. Season with salt and pepper to taste keeping in mind that the soy sauce is already salty. Serve immediately. Chefs notes:Oyster sauce is an excellent all purpose seasoning for pasta, meat and seafood and it will keep indefinitely in the fridge.