In Gae-Baek we open by stepping backwards into an X-knifehand checking block. (Notably, this is the first form that opens with a step back). The "official" explanation for the checking block is that we are blocking a punch.
|Encyclopedia of Taekwon-Do, Vol 11|
|Source: One Minute Bunkai|
This technique is a shoulder-lock and will force the opponent to bend towards their right. We follow with the low twisting kick to their right knee, unbalancing them. We finish with the landing into the front stance "punch" as a takedown: pull the opponent down over your right leg with your left hand as you push with your right hand.
|Example of a twisting kick to the knee after a figure-four lock|