Flying side ways a very slightly downturn (imperceptible but you want the top wing to start coming down)..
Pop the top wing, the kite should flare unevenly. If you're flying right to left to right the kite will look like / Rather than -
At the flare (it comes quick) then you fully release the bottom wing hand (left in this case), and keep pressure on the top wing hand (right in this case).
Better in higher winds, if the winds are low, you need to give a tug and keep pressure on the 'back' hand to get or keep the spin.
Not all kites will do this trick. Very easy on nirvana, transfer, akuji and all my kites do it well. Not easy on deepspace, sea devil (but not very hard), genesis and any kite that doesn't 'settle' deep into a turtle.