Heat the oil in a large non-stick skillet over medium heat. Add the onions, carrots, and salt, and cook until they're starting to soften, stirring occasionally, about 5 minutes.
Stir in the rice, peas, and sesame oil. Cook for about 4 minutes, until the rice is heated through and starting to get crispy, and be sure not to stir the rice more than once or twice.
Meanwhile, in a small bowl, whisk the egg with 1 tablespoon of soy sauce.
Push the contents of the skillet to one side and pour the egg mixture into the empty space. Immediately start stirring the egg with a spatula on that side of the skillet until small curdles form. Then combine the rice with the egg.
Add the remaining tablespoon of soy sauce to the skillet and stir to incorporate. Cook for 1 more minute.
Garnish with sesame seeds before serving, if desired.