Dry-fried chow fun noodles is my little sister's hands-down favorite dish. When done right, the noodles are sticky and tender, intact and distinct from each other, and tinged with a smoky, charred flavor called wok hei (i.e., "wok air," or the essence of the wok).
It acquires this flavor through three sources: high heat charring, from the vaporization of some of the built-up polymers formed from repeated heating of oil in a cast iron or carbon steel surface, and from being repeatedly pushed up and over the lip of the wok where the very hot air rising directly from the burner superheats oils on the surface of the food, adding layers of subtly charred flavor to it.
For these (and other) reasons, you can never replicate the flavor of a cast-iron or carbon steel wok-cooked dish in a Western-style stainless steel or non-stick skillet. (some sources will tell you different. Don't listen to them, no matter how reputable they may be in other cooking fronts).
Here's the thing about chow fun noodles: they're extremely time-sensitive. Made by steaming rice-based batter, the noodles quickly go from supple, slick, and smooth to brittle and stale.
They absolutely must be eaten the day they're made, and shouldn't be refrigerated. This means that unless you live near a good Chinatown or Asian supermarket, or are willing to make your own (not easy), you're unfortunately out of luck.
For the rest of you, read on.
The most common version of dry-fried chow fun (that's dry as opposed to wet, which is served with soupy sauce) in the U.S. is the version with strips of marinated flank steak, scallions, and bean sprouts, all flavored in a simple oyster sauce flavored with fermented black beans. I prefer to replace the beef with some Chinese broccoli (gai lan) or baby bok choy to lighten things up a bit. Either way, the process for cooking the dish is very similar.
"At home, we've got to modify the technique a bit"
At a Chinese restaurant with a high-output burner and a gigantic wok, it's possible to cook everything in one go. At home, we've got to modify the technique a bit.
Home burners are weaker, so to maximize flavor and texture, you've got to allow your wok ample time to preheat (oil should be smoking heavily before adding food), and cook in small batches, searing/stir-frying one ingredient at a time, removing it from the pan, then putting everything together at the end with your sauce.
Chow Fun noodles offer particular difficulties—they break easily and stick together. You might be tempted to separate them in a bowl of water, but this isn't a good idea. Not only will the water that clings to them make them difficult to sear, it'll also get absorbed, making them mushy.
The only trick needed: use plenty of oil, and to turn them gently one they're in the pan using a wide spatula, allowing them to gently fall apart instead of violently breaking them apart.