The acidity of the lime juice will help tenderize the finished dish. It's optional, but 1. the amount is so minuscule that you're not going to taste it and 2. it helps create such tender inner layers. Fish sauce … I know not all of us dig the stuff, but trust me on this — once the eggs are cooked, you’re not going to smell or taste the fishiness. (So far, only one of my fish sauce hater friends has managed to detect the smell, but then his nose works like that of a trained Beagle.) If you absolutely can’t find or stand fish sauce, or if you want to make this strictly vegetarian, use salt, to taste. Khai Jiaw flavored with salt isn’t as good as one flavored with fish sauce, in my opinion. But compared to soy sauce, salt is the lesser evil. I think soy sauce completely ruins what would have been a good Thai omelet. Not only does its dark color mar the bright golden hue, Khai Jiaw with soy sauce also tastes foreign to my Thai palate. Ideally, the lipid of choice is lard as it ensures crispiness. If cooking with rendered pork fat is something your heart yearns for, go for it. But for those who prefer cooking with plant-based lipids, fret not, crispiness can also be achieved with the tips and tricks included here.The trick is to use lots of oil and high heat. When done right, the omelet won’t be oily at all. Thai omelettes are not exactly deep-fried like donuts or fried chicken; they are, for lack of a better term, flash-fried. The egg mixture puffs, crisps, and browns up instantly once it hits the oil. In just a matter of seconds, it goes out of the wok. For this single serving, if both sides of your omelet do not crisp or brown up properly in less than a minute, either the oil isn’t hot enough or you get scared and put in less oil than instructed. The flour is what makes the edges of the omelet nice and crispy. A lot of people skip this step which is fine; this is just one of those tricks of the trade I have learned from chatting with street vendors. I like the crispy edges, so this is what I always do.