Pork tenderloin
Pork tenderloin, also called pork fillet, pork steak or gentleman's cut, is a long, thin cut of pork. as with all quadrupeds, the tenderloin refers to the psoas major muscle along the central spine portion, ventral to the lumbar vertebrae, the most tender part of the animal, because those muscles are used for posture rather than locomotion.
Source: Wikipedia
