These come from behind the ribs and are the most tender cuts, such as tenderloin roasts and the better steaks, such as porterhouse.
The loin may yield the most tender and expensive cuts of beef, but it's not the most flavorful. The choicest portion is the tenderloin, which is exquisitely tender and lean. The top loin and sirloin aren't as tender, but they're a bit more flavorful. Cuts from the loin require very little work to taste great. Indeed, steak lovers consider it almost a sacrilege to marinate them, or to cook them beyond medium rare.