The technique is fairly straightforward, drawing the shape of an ‘L’ is something pretty much everyone knows how to do. Tapping the pokeball, the trainer should then slide it to the left (or right) corner and proceed to slide their finger 3/4 of the way up the side of their screen before releasing the ball.
The same result can be achieved by tapping the ball and shaking it until it sparkles, thereby turning the normal throw into a curveball. Having tested this out personally, I found that the L-throw does, in fact, work…only if you release the pokeball at a certain point on the left side of the screen.
The Pokemon Go GamePress neglects to mention, however, that the size of the Pokemon and the distance away from the trainer affect the point at which the ball will be released. Other than that, this technique is solid and has garnered me a fair amount of Pokemon I would have otherwise wasted my items on.