The Wild Ewt of the Plains of Canada

Forget chemicals with respect to teflon -- it's impervious to anything you'd want to put anywhere near something you'd want to cook in. Or heat. So, your only chance really is abrasives, and anything works. Carborundum paper is probably your best bet, 400 grit should work well. Wrap it around a block of wood and use plenty of elbow grease. Once you're done and have bright metal, use finer grit (800 or finer) to get the worst scratches out, then use something like Brasso to polish it. This should give you a smooth surface before you season it.