Sift the flours, salt, and bicarb soda into a large bowl.
Add the butter and rub into the flour mixture.
Add the buttermilk and dill, and mix to form a dough.
Cover a section of your kitchen bench with glad wrap (I do this to make cleaning up easier) that will provide enough room to knead the dough. Dust with flour.
Turn out the dough onto the floured surface and knead to form a ball shape.
Cover a baking tray with baking paper and place the ball into the middle of the tray and score the middle of the ball with a knife to form a cross.