Preheat the oven to 375 degrees. Line a baking sheet with parchment paper.
In a large mixing bowl, combine the flours, baking soda and salt. Add the oil and buttermilk. Stir until a sticky dough forms.
Turn the dough out onto a lightly floured surface. Knead the dough lightly and shape into a 6-inch round. With a sharp knife, cut an X in the top of the dough.
Place the round on the prepared baking sheet and bake for 25 minutes. The crust should be brown and will give a hollow sound when thumped.
Enjoy warm with butter or a bit of cheese.
Video
Notes
To make as a mix: Take a large ziptop bag or container and label it with the wet ingredients and the baking instructions. Measure out the dry ingredients into the bag. Seal and store until ready to use.Wrap any leftovers in plastic wrap and store at room temperature for up to 3 days.