Just like cast iron, a carbon steel pan needs to be seasoned before its first use. Oil is a must-have for the process, but Cook's Illustrated recommends an additional surprising ingredient for prepping your pan: Potato peels.
Photo by nav in atl.
According to the link below (which also has great tips for maintaining your pan), two potatoes' worth of peels helps to remove the manufacturer's wax or grease off of your new pan. Start by giving the pan a nice, vigorous bath with soapy, hot water and a bristle brush. Dry with a towel and finish drying over low heat. Then, add "1/3 cup oil, 2/3 cup salt, and peels from two potatoes" to the pan and cook it all over medium heat for about 10 minutes, stirring occasionally. (The pan will turn brown; this is normal.) Toss the salty peels, let the pan cool, wipe it out with paper towels and get to cookin'.
How to Season a Carbon-Steel Pan [Cook's Illustrated]