Pour the two flours into a bowl, with the salt and yeast. Mix with a spoon and slowly pour in the milk.  Knead first with the spoon and then pour the dough onto the pastry board and continue kneading by hand until the mixture is firm and smooth.  Wrap the dough in cling film and let it rest in the fridge for 1 hour. Then, divide the dough into two parts.  Flatten the dough with your hands and roll it out very delicately with a rolling pin on a pastry board floured with rice flour. It has to become subtle. Heat a non-stick pan well and cook the piadina on both sides for about 2 minutes.
Tip: to keep them soft after cooking, place them on a plate
on the other and if you can, keep them at room temperature covered with
the film, for 2 days.