“Flash through Back (閃通背)” is a technique of counter attack with the palm strike.
Let me explain it.
You stand on in the right leading stance.
Using the mind drawing technique (引勁), take a posture to induce the opponent’s punch to your face.
(See Photo 1 below)
The important point here is that while drawing the intention of attack,
the engine at your gravity center (丹田) is rotating vertically to keep the moving forward momentum. It is so called a state of “Stationary outside, but moving inside”.
You should keep the state like, for an example, the motorbike can jump out at once right after you release the clutch lever.
The opponent gives you a straight punch targeting your face.
In order for the fist not to hit your face, you have to shift your face 10 cm sideways.
The action to advance the step contains an action of parry that the face is shifted sideways by 5 cm.
For the remaining 5 cm, change the trajectory of the opponent’s punch with your right hand.
You make your right hand rub upward at an angle to the right with synchronizing to the timing of the opponent’s punch.
In order to make the counter-attack successful, using the right hand as insurance, you should step forward toward the opponent’s punch even with a sense of scraping your cheek.
There is a fine line between winning and losing.
The next posture shows that you hit the opponent face with your open-palm.
(See Photo 2 below)
From a view of the opponent side,
“Flash through Back” makes the opponent feel that a flash of light appears suddenly at the front of the face through the enemy’s back.
The name of “Flash through Back” comes from this.
That is what I believe.