Curry leaves are small grey-greenish leaves (a bit like bay), relative of the orange. They can be used fresh or dried. Their aroma is released by its heat and moisture. They are sometimes fried in the oil the food is cooked in, and then discarded.  They are mainly used as an aromatic and flavoring for most curries and soups. When starting a curry or soup dish, put the curry leaves into the oil to fry until crisp.