I first had Pad Thai at a little Thai place in Portland that no longer exists. The sauce was rich and peanutty. I soon found out, after trying the dish at many other establishments, that this wasn't exactly traditional. Still, I loved that original Pad Thai, and was determined to figure it out.
The secret is the sauce. Don't get Pad Thai sauce. Get Satay Sauce. This is my brand, which I get from the local Asian market. Yeah, I could make it myself, but this is better and easier.
Slice half an onion and add it to the pan. Stir it frequently until just translucent. Keep in mind, I like to caramelize the heck out of my onions. If you don't, start throwing in the next ingredients after a few seconds.
Add the softer stuff. In my case, a small zucchini and a third of a red bell pepper. Also add a clove of diced garlic, and a handful of unsalted peanuts. This is where I normally add a small can of bean sprouts, but I forgot 'em. Add a splash of soy. Cook, stirring, for about another three minutes.
Beat two eggs. Move all the veggies over to one side of the pan, and add the eggs and a splash of soy sauce. Stir the eggs until cooked, keeping them mostly separate from the veggies. Skip the eggs if you want to go vegan.