Preheat oven to 450°F. Sprinkle flour on baking sheet, baking stone, or cast iron skillet; set aside. In a large bowl, whisk together flour, baking soda and salt. Add buttermilk and use wooden spoon to stir until the dough comes together. Transfer dough to a floured surface and gently knead for 30 seconds. Using floured hands, form dough into a round loaf and place on prepared baking surface.