Preheat oven to 425 F.
Prepare baking surface: If using a loaf pan, grease it well, and optionally, line with parchment paper. If opting for a free-form loaf, line a baking sheet with parchment.
In a large mixing bowl, whisk together the flour(s), baking soda and salt.
Add buttermilk, stirring until well incorporated into the flour mixture.
Prepare a work surface with about 2 tablespoons of white flour. Turn the dough out onto the surface and gently knead exactly eight (8) times. If it's super sticky, add a tiny bit more flour but go easy. And remember—8 kneads. That's all!
Place dough in the prepared pan or on the baking sheet. Slash the top of the loaf with a serrated knife to allow for steam to escape and the bread to rise well, in the oven.
Bake for 20 minutes at 425 F.
Reduce oven temp to 375 F. Bake for an additional 20 minutes, or until loaf is brown.
Remove from oven to a rack. Allow to cool for 30 minutes before slicing.