While this is incredibly simple in concept it will still need to be explained to students as they may easily use it when doing inside block however a true understanding of the technique means it can be applied in many situations not just those in which it is taught.
So what's happening
Firstly we are again following natural human dynamics, any strike that
is thrown must return. try it yourself execute a kick or a punch and leave
your leg or arm out its uncomfortable even stupid. as it invites extra
blocks or attacks. What we are doing is using that returning energy to
execute our own strike against the opponent. his attack becomes our counter
attack. we are afforded a momentary advantage as most people can not strike
while returning a strike ( true the trained fighter can strike very rapidly
after a strike so as there appears to be no gap between his strikes) but
most people especially in real self defense situations are unable to do
this. so at the same moment his fist is returning to the cocked or chamber
position we are following it in and executing our strike.
As an added bonus the power of our strike is increased by the same amount that your attacker intended to hit you with. This is due to the fact that his backward or returning energy is added to your own forward energy. in effect he or part of him is moving away from you all you are doing is adding to that energy by attaching a blow to it.
We are using the opponents flow not leading his fist but following it in then extending to a strike. all this emphasizes the idea of no gaps as the inside block and the strike are the same movement.
Be aware that it takes some practice to get this right and for it to become a natural idea to the body but well worth the effort once achieved.