Lime leaf, also known as 'kaffir lime leaf', is a key ingredient in Thai cooking as well as other Southeast-Asian cuisines. Note that 'kaffir' is considered a rude word in certain languages, and for this reason it is often omitted these days from most Western packaging, though you will still see it in Asian packaging.

Kaffir Lime Leaf versus Leaves from Lime Trees: Kaffir lime leaves are not the same as leaves from a regular lime tree. Kaffir limes are very different from regular limes in that they are very bitter with bumpy skin. In Thailand, kaffir limes are not consumed but are used mainly in producing household cleaning products. The leaves, however, are very aromatic and can be consumed if cooked or very thinly sliced.

Where to Buy Lime Leaves: Kaffir lime leaves can be purchased fresh, frozen, or dried from Thai or Vietnamese food stores (some Chinese food stores carry them while others do not). A few of the larger regular supermarket chains in the US and Canada are also starting to sell lime leaves - look for them in the fresh herbs section. In Asian food stores, you'll find them either in the fresh produce section alongside the other herbs, or in the freezer section.

Buying Tip: Note that dried lime leaves are not as aromatic or flavorful as fresh or frozen. Lime leaves freeze well, so this is a great way to buy them. One package will last you a year or longer. Take one or two out as you need them, then wrap up the package and return it to the freezer until next time.