Whisk together the potato flour, coconut flour, and salt in a bowl.
Stir in the egg, oil, and water.
Stir until dough comes into a smooth ball. Add more coconut flour, a tablesppon at a time, if the dough is too wet.
Flatten the dough onto a pizza pan.
Bake for 8 minutes at 425F.
Top your parbaked pizza crust and brush the edges with egg yolk.
Add your toppings.
Finish baking for another 10-15 minutes.