Porterhouse steaks are a bone-in steak known for having a large, full filet mignon. The porterhouse is closely related to the T-bone, a cut that sits adjacent on the beef short loin. Compared to the T-bone, the porterhouse has a more substantial filet portion, but less of the center-cut piece of strip. If you love filet mignon, but also want some of the strip's rich flavor, the porterhouse is for you.