Often called the diamond of the culinary world, a truffle is a rare, edible mushroom that is considered to be a delicacy due to its intense aroma and characteristic flavor. They have a firm texture and are most often shaven on top of food before serving, although they can also be used to infuse flavor into dishes. Though there are hundreds of different species, only some — mostly those found in the genus Tuber — are considered delicacies. Truffles grow underground in symbiotic relationships with trees and are difficult to find; as a result, they are usually harvested in the wild by trained hogs and dogs.
Truffles are usually classified mainly based on their appearance, smell, and taste. Found in a variety of regions around the world, many are commonly known by their location rather than their technical name. Their value varies depending on their rarity and specific aromatic qualities; the rarest are the most expensive food in the world.
The French black or Périgord truffle, Tuber melanosporum, is prized for its aromatic and fruity qualities. When fresh, it has a brown-black exterior with white veins on the inside. It ranges in size from a pea to an orange, and weighs up to 2.2 pounds (1 kg). These truffles are found in the Périgord region of southwestern France.