Add salt to egg whites and beat with a fork until slightly fluffy.
Heat skillet to medium to high then melt half of the butter. Adding enough butter is crucial to make lovely looking egg omelet, don't skimp on it.
If there is any ingredients that need a bit of frying, this is the time to do it. Once it is done, take them out and proceed with the next step.
Pour in the egg whites.
In a couple of seconds, the bottom of the egg whites start to solidify. With a fork, rake the egg whites from the sides to the middle, essentially creating a little peak. The remaining liquid egg white should take the pulled up egg white's place.
Run a fork or spatula around the egg, releasing egg whites from the side of the skillet.
Add any optional ingredients like cheese, scallion or ham.
Fold the egg white omelete in half.
Add the other half of the butter, let it melt and fry the egg a couple of extra seconds until golden brown.
Flip the egg white omelete out, garnish and serve.