Both of these hunky steaks come from what’s called the “short loin” primal cut of beef. This is the tender middle zone of the cow that contains the last rib in the animal- the 13th rib. T-shaped bones in this area form the cow's backbone, which are, ta-da, the bones in T-Bone and Porterhouse cuts.
The short loin is worked the least during the animal’s lifespan, thus the reason it is the most tender. All the swank steaks come from this fleshy area including the NY strip, Ribeye, and the Filet Mignon.
Here’s the deal: the Porterhouse is the yin to T-Bone’s yang. Both cuts contain a piece of tenderloin, also called “Filet” for Filet Mignon (Filet is all tenderloin), and a piece of strip put together, separated with the “T” bone. The biggest difference between the two is the size of the tenderloin - if the cut is more generous in the filet department, it’s then labeled as the Porterhouse. The regular T-bone is cut from a smaller piece of tenderloin (between ½ and 1.5 inches wide), and is more shaped like a T, appropriately, whereas the more desired Porterhouse has a more generous piece of tenderloin attached (at least 1.5 inches wide). Both steaks should show up well in size and can be monsterish (up to 24oz), whether you get them from your butcher or are ordering them at a steak house.
Cooking the Cut: Sure, the concept is divine: butcher the loin on either side of the bone to yield a pricy cut containing two crazy delicious cow parts. The problem is that these cuts require different cooking times. The leaner tenderloin side will cook faster than the fattier strip side, so the tenderloin is always at high risk for overcooking.
The best way to cook these chumps is by grilling them or sticking them under the broiler. Pan searing is not recommended – the flesh will shrink up slightly in the pan (as most steaks do), with the center bone distending and holding the meat too high up off the pan. This prevents your beef from attaining that sought-after stovetop sear. Whether the attack is grilling or broiling, just make sure the tenderloin chunk is farther away from the primary heat source than the strip side. Use the hotter edge of the grill to cook the strip. This allows the meat to cook happily and evenly.
The Temp: Going over medium rare is not recommended. These beasts are easiest to cook med-rare or rarer.
Slice: Let the meat take a rest for about 10 minutes to re-absorb juices. Cut the steak close to the bone to separate the tenderloin from the strip. Slice both counterparts against the grain, and serve immediately.