Chop the onion, king oyster mushroom, and green onion into small pieces.

Dice the tofu into cubes. Use firm tofu to prevent breaking.

Marinate the ground pork with mirin and a pinch of pepper.

Mix cornstarch with water to create a slurry.

Heat a pan with cooking oil and sauté the green onion and garlic briefly.

Add the marinated pork and stir-fry on high heat until cooked through.

Add the chopped onion and mushroom, and stir-fry on medium heat until softened.

Add sugar, soy sauce, chili powder, oyster sauce, and doubanjiang sauce. Stir well.

Pour in water and bring the mixture to a boil.

Reduce heat to medium-low and gradually add the cornstarch slurry while stirring.

Once the sauce thickens, add the diced tofu and simmer gently.