The minor downside to a carbon-steel paella pan is the little extra care it requires. Like a cast-iron skillet, it’s prone to rust, so it should be seasoned before the first use and carefully cleaned and re-seasoned between uses.
Before first use remove the label from the pan. If the label does not come off easily, warm the bottom of the pan slightly, then peel the label off. Next, place pan on burner. Fill with water up to handle rivets. Bring water in the pan to a medium boil to remove the clear protective finish. Follow this by washing the pan by hand with soap and water, and then immediately dry (never let pan air dry).
Finally, rub a small amount of vegetable oil on the pan to prevent rust.