ABC storytelling is the art of telling a story (or sometimes a poem) using each of the manual letters of alphabet in order.
An Ameslan storyteller tells a story based on the handshapes of ASL signs from the handshape A to Z in the alphabetical order. For example, "A" for knocking on the door (which is very common), "B" for opening the door, "C" for shaking hands and so on.
The storyteller can use various sequences, such as from A to Z, from Z to A, from AA to ZZ, or reversal.
Ben Bahan and Ben Jarashow. "A to Z: ABC Stories in ASL." DawnPictures. DVD, 2010.
You may also be interested in Numeral storytelling in sign language.