Heat cooking oil in a frying pan then fry both sides of the fish until a bit crispy. Set aside.
Heat a clean pan and pour-in the vinegar. Let boil.
Add sugar, whole peppercorn, and garlic. Cook for 1 minute.
Put-in the onion and red bell pepper. Stir and cook until the vegetables are tender.
Sprinkle salt and then stir.
Put-in the fried fish. Cook for 2 to 3 minutes.
Turn-off heat and transfer to a serving plate.
Serve. Share and enjoy!