The proper cleaning of a Dutch oven is a favorite topic of many cast iron cooks. Some say that excess food must be burned off by turning the oven over in a fire, or by putting the lid on and heating the oven until the food residue inside is burned to a black crust or dust (like a self-cleaning household oven). Others claim it is a mortal sin to use any kind of soap when cleaning Dutch ovens. All, however, agree that you never scrape or scour a Dutch oven. Using metal utensils or wire scrubbers or brushes can remove the curing and allow food to stick in the exposed areas unless the oven is re-cured.
Most frequent Dutch oven users have found that wiping out excess food with a paper towel, then washing the pot with hot soapy water and a sponge will produce a clean and sanitary oven. Remember, after cleaning, be sure to dry the oven completely, then wipe a light coat of your chosen oil over the entire surface of your oven, inside and out, legs included, using a paper towel or cotton cloth. Soon your oven will have a beautiful dark brown or black coat that will be amazingly easy to keep clean.
If you use too much oil while curing or after cleaning your oven, it will become apparent the next time you use it. Each time you take out the oven, remove the lid and smell the inside. If it smells a little rancid, you used too much oil, but don’t worry. Just heat up the oven on your stove or over a fire to allow the oil to melt down and puddle in the bottom of the pot. Wipe out the old oil with a paper towel and you’re ready to go. There is no need to clean the oven again before using.