These cooks are testing for resiliency. As the meat cooks, its flesh becomes less flabby because it loses water and its muscle fibers contract. The more a meat cooks, the firmer and more elastic it becomes. The skill of accurately measuring doneness of meat by its springiness cannot be taught in words. The best way to learn the technique is empirically, by testing the resiliency of the meat each time you use a thermometer
. Eventually, your educated finger will relegate the thermometer to the drawer.
** Asian Recipes