Thoroughly clean the tilapia. Make a small incision on the belly of the tilapia. Thoroughly wash and clean the inside of the tilapia and set a side.
Drizzle the tilapia with the calamansi juice.
In a bowl, mix together, garlic, onion, tomato, salt and ground black pepper. Stuff the tilapia with the stuffing. season the tilapia with salt and ground black pepper. Set a side for 20 minutes.
Wash the banana leaf and pat dry with kitchen towel. Spread some cooking oil so the fish will not stick.
Wrap the fish in the banana leaf and pan grill for 15 minutes on each side over medium low heat.