The Tornado kick, also known as the 540 kick since the leg moves around 540 degrees, is a popular technique which is used in Technique. The same leg is used for taking off, kicking and landing.
There are many variations of the kick including the reverse tornado kick and the crescent tornado kick. If you have watched black belts sparring at a Taekwondo tournament you may have seen this kick already.
Below you will find some good tutorials on how you the tornado kick is achieved.
Some examples of the kick being used in tournaments: