How do you do a corded ridge crochet stitch?
I think what you might be talking about is the reverse single
crochet which gives a corded look. It is generally used as an
edging.
The method is to work a single crochet stitch from left to right
instead of the normal right to left.
I did see a video that said it was corded ridge. The
demonstration appeared to me to be a front post dc, but I can't
speak definitively to that as I'd have to investigate it more.