"Flat, wide rice noodles are most commonly used for this dish. In Chinatown these noodles are made fresh every morning before being sent to the markets. Freshly made, they are wonderful. Old or dry ones are not quite as good. These - and even fresh ones that have been refrigerated or are a little dry - should be steamed for a moment until they are soft and tender then allowed to cool before use. The noodles need to be charred in a wok over a medium heat to give them the smoky taste that is a desired characteristic. A well-seasoned wok is essential for this. Some cooks will rub a little soy sauce onto the noodles beforehand to accentuate the taste. If the noodles are very fresh, this is not really necessary, but if they have been steamed to rejuvenate them, it is wise to do so as the already softened noodles can break up if fried too much. Do not add any oil at this stage but only once they begin to colour, otherwise the noodles will knot and gnarl.
The sauce is thickened with tapioca flour, which gives it a decidedly thick and toothsome texture. It should not be too highly seasoned, as the seasoning should be finished by each person to their taste."