I have just had a new kitchen installed and the black 'thingies' that are on a hob that the pans go onis made of cast iron (sorry don't know what they are called). I have tried to clean them once with soap and water and dried them with a tea towel and kitchen roll but both leave white bits on it. Does anyone know what I could clean them with?
Additionally, if you're oven happens to be a self-cleaning one, just place them in there on the next cleaning cycle... they'll come out exceptionally clean...