Sift the wholemeal flour, put half of the bran aside in the sieve and put the rest back into the flour. Mix wholemeal flour, wheat flour, salt, sugar and baking soda. Add butter and knead crumbly with the flour with your finger. Add 300 ml buttermilk and knead everything into a smooth dough. If the dough is too dry, add some more buttermilk
Form the dough into a round loaf and place it on a baking tray lined with baking paper (approx. 32 x 39 cm). Cut the bread with a floured knife crosswise 1-2 cm deep. Then press a floured stirring spoon handle into the incisions. Brush the bread with water and sprinkle with the sieved bran
Bake in the preheated oven, 2nd shelf from below (electric oven: 200 °C/ convection oven: 175 °C/ gas: level 3) for 30-40 minutes