Pad Thai is often called the signature dish of Thai cuisine. There are several regional variations, indeed it has been said that Thailand has a different curry for every day of the year, but a different pad thai for every cook in Thailand! This is my wife's variation. This variation uses a small amount of khao kua (powdered fried rice), which occurs as an ingredient in several other Thai recipes. You can make a small amount and keep it almost indefinately in a well stoppered jar.
You also need a cup of dry roasted, unsalted peanuts. We roast them in their shells on a charcoal brazier, but you can do it just as well in an oven, or even in a skillet... However they should be freshly roasted to bring out the full flavour for this dish.