Good times, this move. One of my favorite nonplaning transitions, taught to me by ABK's Andy Brandt back in 2000. I saw the move, pointed, and said "teach me that!" He told me I wasn't ready, that I needed to learn the building blocks first. "Teach me all of them right now!" Within a few months I had it. What's particularly fun about it is you can not only use it as an exotic tack, but you can also use it to spin from nose first to clew first, so if you're coming into shallows on your way to shore it's a showy way to get to fin first for the finbuster shallows.
In short, from regular sailing you step to the nose with your back foot, then execute a fin-first backwinded pivot jibe. Once the board has turned 180 degrees flip the sail to head on your new tack, or sail clew first on your new tack, or step to the nose (pulling the mast hand in and letting the clew hand out) to sail in your original direction fin first. It feels great! Shot in Bonaire during an ABK clinic by Tom Lepak.