Make the sauce: In a cup or bowl, mix together the vinegar, olive oil, fish sauce, paprika, salt, sugar, ginger, and water. Set aside.
Arrange the fish: Cut each mackerel fillet into 3 pieces and place them in a single layer in a pan.
Add the vegetables and pour the sauce: Add the carrots, sweet pickles, olives, shallots, garlic, bay leaves, chilies, and ground pepper. Spread everything out evenly, then pour the sauce over the fish.
Simmer and serve: Cover and simmer over medium heat until the carrots are tender, about 30 minutes. Taste and adjust seasoning as needed. If the sauce looks too thin, simmer uncovered for a few more minutes. Turn off the heat.Serve hot with steamed rice or sinangag.
Notes
Mackerel: Atlantic, Norwegian, Boston, or North Atlantic mackerel all work. Look for dark wavy lines on the skin. If unavailable, use sardines, salmon, trout, tuna, or milkfish. Choose firm fish that won’t fall apart while cooking. Sardines and milkfish have more small bones; salmon and tuna fillets are easier and cook faster.
Olive oil: Extra-virgin olive oil gives the best flavor, but regular olive oil works. You can also use avocado or vegetable oil.
Sweet pickles/gherkins: Either works. Cut into bite-size pieces.
Olives: Green pitted olives like Manzanilla are great, but use what you have.
Vinegar: You can use white, apple cider, or cane vinegar.
Tips
Cut vegetables into bite-size pieces so everything cooks evenly.
Lay fish in a single layer for even cooking.
Simmer gently — don’t boil — to keep the fish tender.
This dish tastes even better the next day after the flavors sit.
Storage
Store leftovers in a covered container in the fridge for 3-5 days.
The sauce may thicken when cold because olive oil firms up — that’s normal.
Reheat gently on low heat or microwave in short bursts. Add a little water if needed.