This technique is used when your attacker strangles you from behind.
Your opponent strangles you from the back.
Step with your left leg and place your foot to the left of your attackers left foot and strike with your right elbow to your attackers stomach.
Place your right hand behind your attackers back and grab your attackers right bicep with your left hand (taking your left hand under their right forearm).
Place your right foot to the right of your attackers right foot. Take your left foot further to the left and bend your left knee as shown. Keep your right leg nearly straight with the ball of your foot on the floor. Your calf muscle should be touching the shin of your attackers right leg. Make sure your hips are not in front of your attackers hips.
Simply twist your upper body anti-clockwise and put the heel of your right foot on the floor. Your attackers right leg will be swept backwards as your right hand drags them over your right leg. Once your attacker is on the floor you can strike or continue the fight on the ground by taking up the mounted position.