If you don't have a grill or if weather is keeping you from grilling, you can also prepare your porterhouse steak indoors. When I'm making just one steak, I like to cook it on the stove using a cast iron pan. Just like you would grill, I like to sear it first on high heat then lower the temperature to medium to finish cooking. You can learn more on how to cook a porterhouse steak on the stove here.