Put the vegetable oil in a 10- or 12-inch skillet (preferably nonstick) and place it on medium-high heat.
In a bowl large enough to hold twice the eggs' volume, beat the eggs with a fork just until frothy.
Add the crumbled naem, onion, and chilies to the beaten eggs; stir just until combined.
Add the egg mixture to the hot skillet. Cook the omelet on one side until set and golden, about 2-3 minutes. Flip and cook the other side for another 1-2 minutes.
Serve the omelet with rice. Fish sauce can be served on the side if the omelet isn't salty enough (see note in the post).
Recipe by SheSimmers at https://shesimmers.com/2014/02/soured-pork-sausage-omelet.html