Of all the prized possessions in my kitchen, one of my favorites was also probably the cheapest. I am talking, of course, about my trusted cast iron skillet and the layer of seasoning upon it. In this case, "seasoning" doesn't mean adding salt and pepper to taste, seasoning cast iron refers to the process of cooking oil into the surface of pan, giving it natural non-stick properties.
When you get a cast iron skillet, before you cook a single thing in it, you begin the seasoning process. It's actually super simple: give your skillet a wash with hot water and dry it completely. Rub a little bit of vegetable or olive oil into the surface of the pan and put it upside down in a 350 degree oven. Slide a cookie sheet or bigger pan underneath to catch any oil drips. Leave it for an hour, turn the oven off, and let the oven and pan cool down together. Boom. It's seasoned.
Now that we've covered what you SHOULD do with your cast iron skillet, let's talk about the three things you absolutely should NOT do. Consider these the three deadly sins of cast iron skillet ownership.
Letting It Air Dry
Okay, the cast iron skillet pictured is probably about 100 years old, but we're trying to scare you straight, here. Any water droplets that get to sit around on your skillet will probably cause rust spots. Which isn't a huge deal, but means you need to wash the thing and go to the trouble of re-seasoning it. Do yourself a favor and wipe your skillet down asap after cleaning, and then rub a drop or two of olive oil into the surface. This will help keep it seasoned and protected from rust.
Washing It With Soap
Do not, I repeat DO NOT wash your cast iron skillet with dish soap. Or any soap. I know it takes some getting used to -- we're taught that everything needs to be washed with soap to get clean, but in order to preserve your seasoning, which is the magic holy grail of cast iron skillet cooking, you can't rub any harsh chemicals onto it. Wash your skillet with hot water ONLY. I even go so far as to not use a sponge.
If there's something on your skillet that neither hot water nor helpful encouragement will get rid of, dry your skillet, pour some coarse sea salt into it and scrub with that. It's strong enough to remove stuck-on food, but gentle enough that it won't disturb your seasoning. Then rinse with hot water, dry thoroughly and rub it with olive oil.
Using A Metal Spatula
Same deal here as with a scratchy sponge -- your main goal is to keep the seasoning intact, which means scraping along the cooking surface with metal anything is a major no-no. Plastic or silicone spatulas and wooden utensils are your go-to tools for cast iron cooking. You can usually get away with metal tongs, so long as you're just touching the food and not messing with pan.
An important note: If the unthinkable happens and some black flecks of seasoning start to flake off, you don't have to throw your skillet out. You do, however, have to give the thing a good washing, scrub with salt, and re-seasoning, just like the first time.