Kaffir lime leaves
They are leaves from a kaffir lime tree. Their taste is very specific, thats why it is impossible to substitute them in the dish. They are very common in Thai cuisine, but you will find them in Indonesian cuisine or others too.
They are very thick and not easy to chew. If you use them whole for your meal, remove them before serving.
Recipes with kaffir lime leaves.
To buy kaffir lime leaves US, UK, Europe