I've had a couple of people ask, so rather than try to explain - I, as usual, looked for a video to that showed it instead. This is a classic performance of Sattriya Nritya from India that demonstrates mudras used in dance. Only this dancer does it about 200 times faster than I can.
PS - to D. (as opposed to drj), if you never look at the videos, you might be missing the good bits. :-)