Start heating the charcoal in your grill.
Pass the banana leaf over fire (the stovetop, in our case) to wilt it.
Wipe the tuna collars dry with a kitchen towel.
Wrap a collar in a piece of banana leaf then wrap the package in a larger piece of banana leaf.
Tie the parcel with kitchen twine.
Repeat with the other tuna collar.
Grill the banana leaf-wrapped tuna collars over hot charcoal for 10 minutes per side.
Cut the banana leaf wrappers with kitchen shears.
Serve the inihaw na panga ng tuna as an appetizer or as a main course.