i think you press all the back buttons hard and rapidly, ( L1, L2, R2,R1)

No, you press 1 or 3.

You have to push both of those ^ 1+3 at the same time or the left bumper which is the button to hit for traditional throws, throw escapes and tech sliding as they call it.

It means you'll still take damage but if you time it right after you've been tossed you'll take less damage then you would as if you didn't tech slide recover.

I just hit all 4 face buttons at the same time lol so that I never miss.