Insert the ash tray into the smoker, according to the manufacturer's instructions.
Dampen a clean rag with vegetable oil.
Wipe down the interior surface of the cooker, including the cooking grills. Do not wipe down the charcoal grates or charcoal trays. Rewet the cloth when necessary, so that the interior surface and cooking grills get a light, even coat of oil.
Light a fire in your smoker, according to the manufacturer's instructions for your smoker model. If using lighter fluid, allow the fluid to completely burn off before closing the smoker.
Close the lid of the smoker when the coals are burning strongly, and maintain a heat of 250 degrees Fahrenheit for two hours.
Raise the heat to 400 degrees during the third hour, but to not exceeding 400 degrees.
Allow the unit to cool. Do not touch the exterior of the smoker during the curing process.