Identify your banana-leaf job: nonstick steam barrier, strong wrap structure, or mild leafy aroma infusion.
Choose the substitute that matches the job (parchment for release, foil for barrier/structure, cabbage/plantain for leaf feel).
Size it: cut slightly larger than your food so you can fold edges without stretching or splitting.
Prep for safety and texture: oil parchment lightly, blanch cabbage briefly, and avoid over-wetting rice paper.
Wrap tightly but not crushing—then steam/bake until done, checking the seam stays sealed.