Preheat your oven to 375°F (190°C) and prepare a baking sheet.
In a large bowl, whisk together the flour, baking soda, salt, and sugar.
In another bowl, combine the buttermilk, softened butter, and egg, mixing until smooth.
Gradually add the wet mixture to the dry ingredients, mixing until just combined.
Fold in the raisins or currants gently to avoid breaking them.
Scoop tablespoon-sized amounts of dough onto the prepared baking sheet, spacing them about 2 inches apart.
Bake for 15-18 minutes, or until the edges are lightly golden.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack.