Shred the chicken breast and oyster mushrooms. Slice the onion and green onion thinly. Use vacuum-packed chicken breast for convenience.

Prepare the donburi sauce (soy sauce, mirin, minced garlic, water) and egg mixture (1 egg:2 parts water).

Start with the chicken and mushroom stir-fry: heat oil in a pan, sauté minced garlic lightly.

Add shredded mushrooms and stir-fry until softened. Season with a pinch of salt.

Add chicken breast and green onion, stir-fry further. Add soy sauce and sesame oil, cook for an additional minute.

Switch to a smaller pan suitable for donburi. Sauté the onion until translucent.

Add the pre-cooked chicken and mushroom stir-fry to the pan.

Pour the donburi sauce into the pan and simmer gently.

When the sauce is reduced, pour the egg mixture over the dish.

Cook until the egg sets and detaches from the pan. Serve over rice.