Mix cooked rice, beaten egg, and seasonings (chicken stock powder, salt, pepper, soy sauce) in a bowl.

Heat 1 tbsp salad oil in a pan over medium heat, add the rice mixture, and stir-fry until the rice becomes fluffy. Plate the fried rice.

Prepare mushrooms: separate shimeji and maitake into small clusters, and slice king oyster mushroom into bite-sized pieces.

Heat the remaining 1 tbsp salad oil in the same pan over medium heat. Add minced garlic and ginger, stir until fragrant, then add minced pork and cook until browned.

Add prepared mushrooms to the pan and stir-fry until softened.

Add water and chicken stock powder to the pan, stir, and bring to a boil.

Add sugar, sake, soy sauce, and oyster sauce to the pan, stir, and bring to a boil again.

Mix cornstarch and water to create a slurry, then add it to the pan. Stir until the sauce thickens.