Peel the onions and cut them into thin half rings. Heat the pan over medium heat and pour six tablespoons of soy sauce into it.
As soon as the soy sauce begins to boil, throw the onion half rings into the pan and sprinkle with sugar. Cook, stirring occasionally, for two or three minutes.
In the meantime, cut the chicken fillet into small pieces – no need to chop the meat too much, the finished slices should remain juicy and dense.
Put the chicken in the pan and mix with the sauce. When the meat turns white on one side, gently flip the slices and stew for another couple of minutes. Chicken fillet cooks surprisingly quickly: a maximum of three to four minutes.
In a separate bowl with a fork or a whisk, quickly beat the eggs into a homogeneous mixture. You do not need to add salt – soy sauce, in which the meat is stewed, is already enough salty.
Pour the egg mixture into the pan, trying to evenly cover all the meat. Cover the pan with a lid and cook an omelet for three to four minutes, without interfering, until the eggs are properly set.
Chop green onions. Place warm rice steamed on a serving plate.
On top of the rice gently lay out an omelet – for convenience, it can be divided with a spatula into triangular segments. Sprinkle oyakodon with chopped green onions – and serve hot.