Heat a frying pan (big enough to fit the fish) and add vegetable oil.
Pour lemon or calamansi juice over the fish and rub to get rid of the fishy smell. Season with salt and ground black pepper.
Fry seasoned fish in the preheated cooking oil in a pan until brown and crispy on both sides. Transfer to a platter with a paper towel to drain excess oil. Set aside.
Using the same pan, discard oil from fying the fish; pour about about a teaspoon of olive oil and a teaspoon of sesame oil in the pan.
Saute ginger, garlic, onion, chilli flakes for about a minute; add soy sauce, chili garlic sauce, hot sauce and sugar in a pan and bring to simmer.
Combine broth and cornstarch in small bowl; stir to dissolve cornstarch, add into the pan to thicken the sauce.
Bring to simmer again and let cook for another minute; adjust consistency of the sauce by adding more water for thinner sauce or by letting it simmer for a few more minutes to thicken or add more slurry ( water-cornstarch mixture).