The highest quality dry-cured ham produced in Spain, where it's known as Jamón Ibérico. It's taken from the hind leg of Spanish Ibérico pigs. These pigs, which are raised solely in the southwest of the Iberian Peninsula, are considered to be of higher quality than the white pigs used to produce Spain's serrano ham. Ibérico ham comes in three grades that relate to how the pigs are fed. The highest quality hams are called Jamón Ibérico de Bellota or and are produced from free-range pigs that feed for 6 months (a period called the montanera) on whatever's in the pastures, particularly acorns. During the last few months before slaughter the pig's diet consists solely of acorns. The middle quality level is Jamón Ibérico de Recebo--pigs that spend time in the pasture and then are a fed a mixed diet of grains and acorns. The final quality level is called simply Jamón Ibérico or Jamón de Pata, the latter meaning "black leg" and referring to the fact that most of the Ibérico pigs are black. The pigs of this last grade are fed with an authorized diet of grains but no acorns. Aging for Ibérico ham varies from 1 to 3 years or more. Production is very limited, which means these hams are some of the most expensive in the world.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.