Cut chicken breasts into bite-sized pieces. Slice onion and green onion thinly. Slice mini king oyster mushrooms lengthwise and halve them.

Mix eggs with 1 pinch of salt, 1 tbsp of water, and 1 tbsp of sesame oil. Stir lightly until 70% mixed, leaving some separation between yolk and whites.

Prepare the sauce by combining soy sauce, mirin, sugar, and black pepper. Adjust seasoning to taste.

Heat a pan with a generous amount of oil and fry the chicken until white and cooked through.

Add the sliced vegetables to the pan and stir-fry until softened.

Pour in 2 cups of rice water (or plain water) and the prepared sauce. Bring to a boil.

Once the broth starts bubbling, pour the egg mixture in a circular motion over the pan. Cook for about 1 minute, then turn off the heat and let the residual heat finish cooking the eggs.