I don't have much to say about kaffir lime leaves since I don't use it too much in my cooking. Kaffir lime leaves add a lovely citrus note to many curries and seasonings without making the food taste too sour. I associate the leaves mainly with Thai cuisine, although there's a random Vietnamese and Indonesian recipe thrown in as well.
The double leaves of the kaffir lime are a little thicker than normal lemon leaves, although in a pinch, I've used Meyer lemon leaves off my uncle's tree with no problems. The leaves can be left whole to stew in curries, or finely chiffonaded and added as a garnish.
The peel of the kaffir lime is used in making curry paste, but the lime itself isn't all that juicy.
They can be found in most Asian grocery stores for just a buck or two. Freeze what you don't need. The leaves retain their greenness pretty well for several months.
Recipes using kaffir lime leaves:
Ga Nuong La Chanh (Vietnamese Grilled Chicken in Kaffir Lime Leaves)
Indonesian Beef Rendang
Tom Kha Gai (Thai Galangal and Chicken Soup with Coconut Milk)
Tom Yum Fried Rice with Shrimp Roe and Kaffir Lime Leaves
Tom Yum Goong Kai (Thai Hot and Sour Shrimp and Chicken Soup)
Other ingredients can be found in Peek in My Kitchen: Guides, How Tos, & Ingredients.
1 year ago today, How to Season Black Steel Pans.
2 years ago today, Jovino - San Francisco (Marina/Cow Hollow (Closed).
3 years ago today, Uppsala - Sweden: Birthplace of Celsius.
4 years ago today, Tom Kha Gai (Thai Galangal and Chicken Soup with Coconut Milk).