The movement where the feet describe an '8' in 2 steps,
Example: first the right foot forward and with a slight rightward movement at the end, then the left foot joins the right one, the body is turned 180° clockwise and the mirror movement is done with the left foot, back to the original position.
Can be repeated as much as wanted.
video sample (http://www.infoimnetz.de/tango/heidelberg/dvd_en.html) via Flickr (http://www.flickr.com/photos/smoothouse/242274124)