This movement in Bassai is done slightly different in Shotokan. The movement starts from a left side forward knife-hand block (the previous move), and represents an opponent grasping your blocking (left) arm with his right (he is right side forward). You then execute a two-handed grasping block by reversing his grip on your left arm, and swinging your right arm in an exaggerated wide clockwise arc, from down low to as far over his head as your reach allows, while wrapping your right wrist over his trapped arm and pinning his grasping wrist to your forearm with your left hand. This forces him to bend the trapped wrist; then you pull both of your arms straight downward and inward, thereby performing a wrist lock on his trapped right arm. The wrist lock will immobilize him, forcing him to bend both his forward elbow and his forward knee. Please note that this technique is accompanied by an overshift to your left of the contracted front stance. Then immediatley pull both your arms (and subsequently his trapped arm) to your abdomen, rotate slightly and execute a low-level side thrust stamping kick to his forward knee.

I know this is a rather convoluted description of what has proven to be a very effective technique, but words can only do so much. This technique does have its limitations though, especially if the opponent is much taller than you are, as it will be difficult to get the wrist lock on him if he is not forced to bend his wrist during the movement. In that case, I would just shoot him instead.

Kyoshi