Porterhouse steak actually contains two highly prized cuts of beef. It is bone-in, containing a T shaped cross section of lumbar vertebrate. Porterhouse steak has a section of short loin meat (fillet) on one side and a large sirloin steak on the other. This truly makes it fit for larger appetites, who want the best of both worlds - the rich flavour of sirloin and the tenderness of fillet steak at the same time.