Scrub your brand-new cast iron dish with a little bit of soap and a scouring pad or other rough brush. This will remove the wax or shellac coating used to protect the dish during transportation. If you don't remove every bit of the coating, it will negatively affect the taste of any food cooked in the dish.
Dry the dish thoroughly after rinsing, the first time and every time. Apply a coating of vegetable oil or shortening to the cooking surface of the dish. Use a vegetable-based product instead of an animal-based product to keep the dish from developing a rancid smell.
Preheat your oven to 350 to 400 degrees, and bake the oiled cast iron dish for one hour. Repeat this seasoning process as needed, to develop a full nonstick coating on the dish.
Cook the first few meals in the dish by frying, if possible. The additional coatings of hot oil will help to seal the nonstick coating.
Wash the dish after each use with a simple hot water rinse. Never use soap on a seasoned cast iron dish. Use a nonmetal brush with salt as an abrasive, to remove any burnt-on food, but do not allow the dish to soak. If you use a metal scouring pad to remove food, re-season the pan.
Store the cast iron dish with a paper or cloth towel covering the cooking surface. This protects the nonstick coating and prevents the cast iron dish from dirtying other dishes with grease, which can leave black marks.