Cast iron has long been prized for its cooking qualities. A well-seasoned piece of cast iron has a non-stick coating that eggs will slide around on, and when properly kept, cast iron will last for several lifetimes. Once heated to the desired temperature, cast iron retains heat superbly in comparison to other common metals. This makes it an excellent choice for cooking and baking in, as cast iron evens out any variations in cooking temperature. Although normally used on the stove top, cast iron is also an excellent choice for roasts cooked in the oven.
Trim excess fat from the surface of the roast, if desired. It is best to leave at least 1/4 inch of fat in order to prevent the roast from drying out in the oven. If cooking a rolled and tied roast, check the twine to ensure that it holds the roast firmly together. If not, retie the loose portion with butcher's twine.
Season the roast lightly with salt and pepper. Rub it with a dry seasoning mix or immerse in a marinade, if desired. Refrigerate for two to four hours, or as directed in your favorite recipe.
Remove the roast from the refrigerator and wipe off any excess marinade, if applicable. Use clean paper towels to pat dry the surface of the roast.
Preheat the oven to 325 degrees Fahrenheit. Place the skillet over a burner and heat it, dry, until it is hot and almost smoking.
Place the roast in the pan, fat side down, and sear it until well browned. Turn the roast until all sides are equally well seared. Roll the roast until the fat side is at the top. Cover loosely with aluminum foil and place the skillet in the preheated oven.
Roast until the pork registers an internal temperature of 150 to 160 degrees Fahrenheit when tested with a thermometer. The desired end temperature is 160 degrees Fahrenheit, but the internal temperature of a large roast will continue to increase after it has been removed from the oven.
Allow the roast to rest for 10 to 20 minutes before carving and serving.