Preheat your oven to 425°F (220°C). Grease a cast-iron skillet and set aside.
In a large bowl, whisk together the flour, baking soda, and salt until well combined.
Make a well in the center and gradually add the buttermilk, mixing with a wooden spoon until a dough forms. Do not overmix.
Turn the dough onto a floured surface and gently knead for a minute until the dough comes together.
Shape the dough into a round loaf and place it in the prepared skillet. Using a sharp knife, cut a cross on top of the dough.
Bake in the preheated oven for 35 minutes or until the bread is golden brown and sounds hollow when tapped on the bottom.
Remove from oven and let cool on a wire rack. Serve warm or at room temperature.