Fresh banana leaves are far more flexible and watertight than frozen leaves. To start, rinse leaves in warm water and dry them with a clean towel. Right before using them, pass the leaves over a hot flameāeither a gas range, grill, or open fireāin order to make them more pliable.
When working with frozen leaves, let them defrost on the counter overnight, in the refrigerator for a day, or out in the sun for a few hours. As with fresh leaves, rinse them, dry them, and pass them over a flame before using.