First make a starter dough.

Whisk the yeast into 50g of the water until completely dissolved.
Add the salt, 25g of the all-purpose (plain) flour and 50g of the cake (superfine plain) flour.
Place in a mixer and knead with a dough hook for approximately 4 minutes, until a dough forms.
Knead with your hands until smooth.
Place in a bowl, cover, and leave in a warm spot to rise until doubled in size – approximately 2 hours.
When starter dough is ready, place the remaining flours in a mixer.
Add 5g of the risen dough and the potassium solution and mix with a dough hook until evenly incorporated – approximately 5 minutes.
Feed the dough through an electric sheeter about 20 times, until smooth and elastic.
Wrap in plastic wrap (cling film) and allow to rest for 30 minutes.
Cut the dough sheets into 4.5g pieces and form into thin, circular wrappers using an electric sheeter or a small rolling pin.