Preheat your oven to 425°F (220°C). Line a baking sheet with parchment paper or lightly grease a cast-iron skillet.
Mix the dry ingredients. In a large bowl, whisk together the flour, baking soda, and salt. Stir in the raisins so they are evenly distributed.
Add the buttermilk. Make a well in the center of the flour mixture and pour in the buttermilk. Stir gently with a wooden spoon or your hands until a shaggy dough forms.
Knead lightly. Turn the dough onto a floured surface and knead it just a few times to bring it together. Don’t overwork it—rustic is the goal here!
Shape and score. Form the dough into a round loaf and place it on your prepared baking sheet or skillet. Use a sharp knife to cut a deep cross in the top—this helps it bake evenly and, according to legend, lets the fairies escape (because nobody wants angry fairies in their bread).
Bake. Pop it in the oven for about 30-40 minutes or until the crust is golden brown and it sounds hollow when tapped on the bottom.
Cool and enjoy! Let it cool on a wire rack for at least 10 minutes before slicing. Serve warm with butter, jam, or alongside your favorite hearty meal.