Choose T-bone steaks that have a bright, cherry-red colour, without any greyish or brown blotches. Steaks should be firm to the touch rather than soft. Also select steaks that do not have excessive juice in the package, which may indicate improper storage.
If it will take longer than 30 minutes to get home from the store, place the steaks immediately after purchasing in a chilled cooler you've brought with you. It's important to keep the beef cold.
Once home, place the steaks in the refrigerator even before you unpack your other groceries. Plan to cook the T-bones within three days or freeze for later cooking.
Season T-bones with a dry rub or marinade if you prefer about four hours before cooking. If dry-seasoned, steaks can sit refrigerated overnight, that's fine, but be aware that steaks placed in a vinegar or wine-based marinade for more than 24 hours can get mushy and lose texture.
Bring grill to correct temperature, which takes about 45 minutes. You want medium to medium-low coals for cooking T-bones. You don't want the fire too hot because the key is searing the outside of the steak to create a caramelized crust that seals the steak juices on the inside. You don't want to char the outside to a blackened crisp.
Turn T-bones with tongs, not a fork, as they cook. A fork pierces the beef and allows the flavourful juices to escape.
Test for desired doneness by pressing your finger onto the surface of the steak. A medium-rare steak will be springy with slight resistance but not hard. A medium steak will feel firm with minimum give. The medium-rare steak is pinkish red and hot in the centre. The medium steak is pink and quite hot in the centre.
Once cooked to perfection, which will take no longer than 10 to 15 minutes, remove T-bones from the grill onto a platter and let the steaks sit for 2 to 4 minutes to set the juices in the meat. Carve and enjoy.