Cloves are a spice which come from the unopened buds of the Evergreen Clove tree. Shaped like a nail they are sold whole or ground and are used to flavor sweet or savory dishes. They are often used in making a bachamel sauce. In one recipe you will be instructed to nail a bay leaf to an onion by using the cloves as thumb tacks. Used sparingly they have a wonderful flavor but a heavy hand can yield bad results.
