Prepare the cleaned and scaled tilapia by cleaning it after you bought it from the market. I don't like to emphasize it further but for the sake of clear instruction, be sure that the fish was sliced at the back to get the internal organs out. So that way you can put the stuffing inside. If the cut is at the abdomen, the fish will look messy. Clean the tilapia in running water and drain. Rub every fish with rock salt then set aside.
Prepare the stuffing by combining the onions, tomatoes, celery, patis and magic sarap. Mix thoroughly then fill each tilapia with the stuffing using your hands and a spoon.
Then wrap each fish with banana leaves. You don't need to wrap it like a package, see the photo below so you can picture it clearly.
Heat the cooking oil, about 3 to 4 cups in a frying pan. Then put fish and cover it immediately because you might be spilled with boiling oil. That is why is is called pinaputok because of the fire cracker sound while frying the tilapia.
When there is no cracking sound already, about 2 to 3 minutes, turn the fish on the other side and watch out again and cover the lid. After 2 to 3 minutes, it is ready to serve.
For the sauce: Combine kalamansi juice and patis