Heat the vegetable oil in a frying pan over medium-high heat.
Crack the egg into a small mixing bowl. Add the chopped green onions, fish sauce and beat together with a fork.
In a small/medium frying pan, heat the oil until very hot and shimmery. Carefully pour the egg into the center of the pan and fry for a minute or two.
Using a fork or thin spatula, flip the omelet to the other side and cook for another minute or two.
Turn off the heat and serve the Thai omelet on a bed of warm steamed rice with veggies and your sauce of choice. Enjoy!