Clean thoroughly with soap
Scrub as best as you can with a non metal abrasive. Stay away from steel wool as it will lead to corrosion down the road.
Soak in a vinegar solution
Use 50% vinegar and 50% warm water. Soak for about 30 minutes.
You won't see 100% of the oxidation removed but close to it. Keep in mind, the oxidation is totally safe and will not impart any bad flavors but its still nice to remove most or all of it.