Kikoken
Chun-Li's fireball-throwing move, established in Street Fighter 2 Turbo. It has undergone a few modifications through the generations and series since then. Depending on the game, it is executed with either a forward half-circle and a punch or by holding back a couple of seconds then pressing forward and a punch. In Super Street Fighter 2 and its Turbo update, the speed and length of the kikoken are determined by the level of the punch; a Kikoken using strong punch flies the fastest but burns out more quickly and doesn't go as far.
Chun-Li used to have a disadvantage against characters like Ryu, Ken, Dhalsim, Guile, and Sagat before she got her Kikoken. Now she can knock the hell out of them from a distance.