After an 8 hours EvapoRust soak, rinse in warm, soapy water and a wipe with a washrag. Then a coat of room temp mineral oil, wiped off.
EvapoRust is the lazy man's cleaning dream. Expensive, but it sure works. (Although I bought a 3.5 gallon bucket with dipping basket for about $50 from Amazon Prime last year.)
I needed this pan like a hole in the head, but has one of nicest Made In USA markings I've seen on this pan.
Tom