In the bowl of a blender, pour the wheat and corn flour, add salt and sugar, turn on for a few seconds to mix the ingredients.
Add the cold butter, cut into small cubes, turn on the blender again and mix the ingredients until fine crumbs.
Then pour 2 tablespoons of ice water into a bowl and grind everything for a few seconds until the crumbs turn into quite large pieces of dough that form into a lump when compressed.
If the dough crumbles, you can add another 2 tablespoons of ice water, 1 spoon at a time.
Pour the resulting dough into a plastic bag, form a disk from it and put it in the refrigerator for 1 hour.
Plums wash, dry, then cut into 4 parts.
Put the plum pieces in a bowl, add the starch and mix well.
In another bowl, mix the sugar with the cinnamon.
Put the dough on baking paper, lightly sprinkle it with flour and roll out into a circle with a diameter of 35 cm (I came out smaller).
To move the paper with the dough on a baking sheet. Put the filling on the dough, not reaching the edge of 5 cm, evenly sprinkle the plums with a mixture of sugar and cinnamon.
Wrap the edges of the dough in a circle (directly with the paper, then gently Unscrew it), then lubricate them with the yolk, whipped with 1 tsp. water (I did not lubricate).
Bake in the oven, preheated to 180°C, for 35-45 minutes, until the dough is browned and the filling begins to bubble.