These dark-green spear-shaped leaves are highly aromatic and pleasantly bitter, a mainstay of Indian cooking. As the name suggests, they smell like curry, but they are not an ingredient in curry powder, which is a multispice blend. Indian cooks generally fry curry leaves in cooking oil (often with other whole spices) before adding other ingredients. They look a little like bay leaves, but unlike bay, curry leaves can be eaten.
Curry leaves are available fresh, frozen, and dried; the fresh are more flavorful. The fresh leaves are usually sold on the stem; strip the leaves off to use them.
Fresh curry leaves in a zip-top bag will keep for about two weeks in the refrigerator. They may also be frozen for up to three months, though they'll lose some potency.