Clean the Spanish mackerel, remove the bones, and cut it into bite-sized pieces.

Pat the mackerel dry with a paper towel and season lightly with salt, pepper, and cooking wine. Let it marinate for 10 minutes.

Place 4 tbsp of cornstarch in a plastic bag, add the marinated mackerel, and shake to coat evenly.

Heat oil in a pan and fry the coated mackerel until golden on both sides.

Mix soy sauce, oyster sauce, cooking wine, sugar, sesame oil, sesame seeds, and water in a bowl to create the sauce.

Slice green onion, red chili, and green chili into small pieces.

In a pan, add the sauce mixture, minced garlic, and the sliced vegetables. Simmer briefly.

Add the fried mackerel to the pan and coat it evenly with the sauce. Simmer until the sauce thickens.