First, mix both flours with soda and salt in a bowl. Then we add buttermilk and a sticky mass is formed. Lightly flour the work surface and lightly roll out and fold the dough several times. Do not knead! Shape into round loaves and cut deeply into a cross. Dust with flour and place on a baking sheet lined with baking paper. Bake for about 30 minutes until the bread is almost golden. Let it cool and best consume it the same day.