In a mixing bowl, combine the crushed garlic, sliced onion, salt, crushed black pepper, and vinegar. Stir well to mix the ingredients thoroughly.

Place the butterflied bangus in a shallow container, skin side down. Pour the vinegar marinade over the fish, ensuring it is fully coated. Cover the container and let the fish marinate in the refrigerator for at least 4 hours, or ideally overnight, to let the flavors fully absorb.

After marinating, remove the bangus from the marinade. Drain any excess liquid, put it on a drying rack or pat the fish dry with paper towels. This helps reduce oil splatter during frying.

In a large frying pan, heat 1 cup of cooking oil over medium heat until hot.

Carefully place the bangus in the hot oil, skin side down first. Fry until the skin is crispy and golden brown, then flip to cook the flesh side until it becomes a light golden color.

Serve the Daing na Bangus hot with steamed rice and a side of vinegar with chopped garlic and chili for dipping, if desired.