where can I buy banana leaves?
Sri Lankan grocery stores carry them. I believe they are frozen and you need to thaw them. I am not sure if they carry fresh banana leaves. The leaves are used to make this rice dish that has curries and then is baked in the banana leaf. It is called lamprice or lampries.
A lot of Tamil Sri Lankans eat their food off of a banana leaf on special occassions.
I've seen them in a few Asian grocers. I think I just saw them at the recently renovated grocer on the west side of Spadina north of Dundas. It is in a basement and I think its called Orient something. Usually they're frozen. I've seen fresh now and then -- usually at festival times.
Go to one of the Latin American grocers in Kensington Market. I got mine there (can't remember which store - they all stock'em) to make cochinita pibil, a Mexican dish of pork butt marinated in orange juice and annatto, wrapped in banana leaves, and slow-roasted in the oven.