Porterhouse steak, a cut consisting of a top strip loin and a portion of the tenderloin, is a one to two-inch thick display of pure backyard grill glory; that is, when it's cooked correctly. Fortunately, you can avoid disappointingly tough, over-cooked porterhouse steaks by understanding the basic precepts of successfully cooking thick steaks on the grill -- how to prepare the meat in advance, how long to cook the cook the steaks and how to correctly judge their doneness. Master these basic steps and you'll be able to turn out beautifully seared, juicy steaks good enough to rival the fanciest steakhouses, and at a fraction of the cost.
Warm to Room Temperature
Porterhouse steaks -- and, in fact, all steaks -- should be allowed to warm to room temperature, or 70 degrees Fahrenheit, before cooking. When cold steaks come into contact with a blazing hot grill, the meat tissue contracts sharply, resulting in a tough, hardened exterior crust. By contrast, if you remove the steaks from the refrigerator 30 to 60 minutes prior to the time you plan to begin grilling, you will produce a finished steak that is tender and evenly cooked. If room temperature is significantly higher than 70 degrees Fahrenheit, let the meat sit out for no more than 30 minutes; likewise, if the temperature is much cooler than 70 degrees, you may need to let the meat sit out for a full hour. However, leaving meat at room temperature could result in food-borne illness, so you should use this method with caution.
Resist the temptation to season Porterhouse steaks with salt before grilling. Since salt draws moisture out of meat tissue, salting the steaks before placing them on the grill will cause water to accumulate at the meat's surface and you'll end up with grayish, partially steamed Porterhouse steaks, not the high-heat seared taste, texture and brown appearance you're craving. Cook the steaks first, then season with salt and pepper immediately before serving.
Make certain the grill is extremely hot by allowing it to heat for 10 minutes before adding the steaks. Place the meat on the hottest portion of the grill and cook, undisturbed for 7 to 10 minutes per side for rare meat or 8 to 12 minutes for medium-rare. If you'd like the steaks to have cross-hatch marks, turn the meat 30 degrees after the first three to four minutes of cooking time has elapsed for each side.
You can use the finger, or "poke," test to determine the doneness of your Porterhouse steaks. Poke several sections of the meat with your index finger; a rare steak will feel soft to the touch, while a medium rare steak will have some resistance. A more reliable method to judge doneness is to use a meat thermometer. Meat cooked rare will register around 120 degrees Fahrenheit, medium rare around 125 degrees, and medium 130 to 135 degrees. When your steaks reach the appropriate temperature, remove them from the grill and let them sit for 15 minutes. Don't overshoot the recommended temperatures because the steak's temperature can rise as much as 10 degrees after cooking. The US Department of Agriculture recommends using a meat thermometer to test the internal temperature of your steak to ensure it reaches a temperature of at least 145 degrees F before you consume the meat.