Mark, I got the definition from Chambers Dictionary (but I don't have the version to hand) . Originally, it was a turn in skiing practised at Telemark, but now also applies to a skating move of the type described in your clue!
Google with "telemark to ronde" and you'll get one such site of professional dancers trying to flog a video of how to do the telemark (without skis or skates)
mark, Quoting verbatim from Chambers Ninth Edition, I have telemark noun (in skiing) a sudden turn on the outer ski; (in ballroom dancing) a step incorporating a heel pivot.