Remove scales, gills, and insides of milkfish; cut off part of the tail. Pound fish firmly to loosen it up. Cut fish open lengthwise from the backside. Scrape meat out into a saucepan over medium-high heat, being careful not to tear the skin.
Squeeze 1/2 the lemon onto the fish meat; add soy sauce. Bring to a boil; cook until liquid is absorbed, about 2 minutes. Remove from heat and let cool, 5 to 10 minutes. Remove fish bones from the meat.
Heat olive oil in a skillet over medium-high heat. Add onion and garlic; saute until onion is translucent. Add the fish meat, peas, carrot, celery, raisins, salt, and pepper. Cook until fish is opaque and flavors are combined, about 5 minutes. Let filling cool until safe to handle, at least 7 minutes.
Stuff fish skin with the filling. Sew up any openings to seal in the filling.
Heat vegetable oil in a deep saucepan. Fry the stuffed fish whole, turning as needed, until golden brown and crisp, 5 to 7 minutes. Place on a plate or flat work surface and slice fish crosswise.
We have determined the nutritional value of oil for frying based on a retention value of 10% after cooking. Amount will vary depending on cooking time and temperature, ingredient density, and specific type of oil used.
Per Serving: 264 calories;16.3 g fat;
18.4 g carbohydrates;
14 g protein;
30 mg cholesterol;
344 mg sodium.