I believe what they did was to spread a thin layer of chocolate onto a flat surface, probably marble.
You can find plastic and rubber combing tools at any craft (Michael's, Hobby Lobby) or hardware store (Ace, Home Depot, Lowe's). They often come in triangle or square shapes with different widths cut out of each side to create patterns. I'm assuming they used a similar tool and dragged it from one end of the sheet of chocolate to the next to create the curls. Then for the stripes which are left, they took a thin, flexible metal spatula and scraped them along their length to create the same curls.
Hope that helps.