Filet Mignon  The most expensive cut of beef comes from the small end of the tenderloin.  Boneless, it is ideally 2 - 1/2 inches thick and 1-1/2 to 3 inches in diameter.  This is the most tender of all beef cuts.  It is lightly marbled and mild flavored compared to other cuts.    On restaurant menus it is called Filet Mignon, Tournedos, Medallions, Filet de Boeuf and Tenderloin Steak.