Preheat Oven: Preheat your oven to 200°C (400°F/Gas Mark 6). Lightly flour a baking sheet.
Combine Dry Ingredients: In a large mixing bowl, combine the flour, bicarbonate of soda (baking soda), and salt.
Add Buttermilk: Make a well in the center of the dry ingredients and pour in the buttermilk.
Mix to a Soft Dough: Using a round-bladed knife, quickly mix the ingredients together until you have a soft, slightly sticky dough. Be careful not to overmix!
Shape the Dough: Turn the dough out onto a lightly floured surface and gently shape it into a round, about 4cm (1 1/2 inches) thick.
Place on Baking Sheet: Place the dough round on the prepared baking sheet.
Cut a Cross: Using a sharp knife, cut a deep cross into the top of the loaf, going almost all the way through. This helps the bread to bake evenly.
Bake: Bake for 30-35 minutes, or until the bread is golden brown and sounds hollow when tapped on the bottom.
Cool: Transfer the soda bread to a wire rack to cool slightly before serving.