Preheat the oven to 425°F (220°C). Lightly flour a baking sheet or cast iron skillet.
Mix dry ingredients – In a large bowl, whisk together the flour, baking soda, and salt.
Add buttermilk – Make a well in the center and gradually pour in the buttermilk. Stir until a shaggy dough forms.
Shape the dough – Lightly knead for 30 seconds until it comes together. Do not overwork.
Form a round loaf – Place on the prepared baking sheet and use a sharp knife to cut a deep cross on top.
Bake for 30-40 minutes until golden brown. The bread is done when it sounds hollow when tapped on the bottom.
Cool on a wire rack before slicing. Serve warm with butter or jam.