Q: How many steps are there in Tango?

A common reply is 3 - forward, side, back

...or 6 - forward, side, back with both left and right legs

However, I  love this answer (which gets to the essence of the improvisational nature of tango) by Gery Rudolph from the Seattle-based tango school Got 2 Tango:

A: "There is really only one step in tango — the next one — if you decide to take it...

(you might also need or want to hang out in the same place for awhile)." 

Gery Rudolph with her life and teaching partner Greg Thomsen