This technique is used when your attacker throws a straight punch.
When your attacker throws the punch, step forward with your left foot and block the strike with a basic inside forearm block.
Twist anti-clockwise on the ball of your left foot and take your right arm behind your attackers back. Bend your left knee to pull your attacker onto your back. Also take your right foot off the ground ready for the sweep.
Straighten your left leg to lift your attacker off the ground and throw your right leg backwards to sweep your attackers legs.
As you sweep your attackers legs, twist your upper body to perform the throw.