any ideas on keeping a cast iron steamer in good shape? I cook with cast iron all the time, and i spend time cleaning/seasoning properly... but something just seems...wrong...about steaming water in the cast iron all the time. I am wondering about a couple drops of vegetable oil in the water, to help keep the inside surface 'healthy'. I have hard water (well water) and i use a softener, but i still see rust and mineral deposits on the bottom of the steamer. Any tricks?