Start your preparation by scaling the bangus (kaliskisan ang bangus) if you prefer to remove the scales. Take your sharp knife (kutsilyo) and make a careful butterfly cut along the belly of the fish, opening it flat like a book. Remove all the internal organs (tanggalin ang mga lamang-loob) and rinse the fish thoroughly under cold running water.
Next, locate the backbone of your butterflied bangus. Starting from the head, gently pull the backbone toward the tail to remove it completely. Use tweezers to carefully remove any remaining small bones (mga maliliit na tinik). Once deboned, rinse the fish again and pat it completely dry using paper towels (tuyuin ng mabuti gamit ang paper towel).
In a large non-metal bowl, prepare your marinade by combining one cup of Filipino vinegar, five crushed cloves of garlic (dinurog na bawang), one teaspoon of cracked black peppercorns (dinurog na paminta), and one teaspoon of salt (asin). If you enjoy spicy food, you may add crushed Thai chilies (dinurog na siling labuyo). Mix these ingredients well until the salt dissolves completely.
Place your prepared bangus in a shallow container (lalagyan) and pour the marinade over it, making sure the fish is completely covered by the solution (siguruhing nalulubog ang isda sa marinade). Cover the container and place it in your refrigerator set at 4°C/39°F. Let the fish marinate for at least 8 hours or overnight, but do not exceed 12 hours as this can make the fish too soft (malambot).
When you're ready to cook, remove the marinated fish from the refrigerator. Take the bangus out of the marinade and pat it very dry with paper towels (tuyuin ng mabuti). This step is crucial for achieving crispy skin (magkaroon ng malutong na balat).
Heat your frying pan (initin ang kawali) and add enough cooking oil to cover half the thickness of the fish. The oil must reach exactly 180°C/350°F before frying. If you don't have a thermometer, test the oil by inserting a wooden chopstick - the oil should bubble steadily around it but not too vigorously.
Carefully place your bangus in the hot oil (maingat na ilagay ang bangus sa mainit na mantika). Let it fry undisturbed for 3-5 minutes until the bottom side turns golden brown. Using tongs (sipit), carefully flip the fish only once and cook the other side for another 3-5 minutes. The internal temperature should reach 63°C/145°F for food safety.
Once cooked, lift the fish from the oil using your tongs and let it drain on paper towels (patuyuin sa paper towel) to remove excess oil. The skin should be crispy and golden brown, while the flesh inside remains moist and flaky.
Serve your daing na bangus immediately while hot (ihain habang mainit pa) with garlic rice (sinangag), fried egg (pritong itlog), and a side of tomato and onion salad (ensaladang kamatis at sibuyas). Prepare a dipping sauce (sawsawan) by combining vinegar with crushed garlic, cracked black pepper, and chili peppers if desired.
If you have leftover cooked daing na bangus, let it cool completely before storing in an airtight container in the refrigerator. It will keep well for up to three days. When reheating, warm it in a pan over low heat (mahinang apoy) with a small amount of oil, or in an air fryer at 180°C for 3-4 minutes. Avoid using the microwave as this will make the fish rubbery (makunat).