Preheat your oven to 425°F (220°C). Line a baking sheet with parchment paper.
In a large mixing bowl, combine flour, sugar, baking soda, cream of tartar, and salt.
Add the cold, diced butter to the dry ingredients. Using your fingertips or a pastry cutter, rub or cut the butter into the flour mixture until it resembles coarse crumbs.
If using raisins or currants (or chocolate chips), add them to the flour mixture and toss to combine.
Make a well in the center of the mixture and pour in the buttermilk and vanilla extract. Stir until just combined, being careful not to overmix.
Turn the dough out onto a lightly floured work surface. Gently knead it a few times until it comes together. Pat the dough into a round dough circle, about 1 to 1.5 inches (2.5 to 4 cm) thick.
Use a floured round cutter to cut out scones from the dough. Place them on the prepared baking sheet, leaving some space between each.
Brush the tops of the scones with a bit of buttermilk for a golden finish.
Bake in the preheated oven for 12-15 minutes or until the scones are golden brown and cooked through.
Remove from the oven and transfer the scones to a wire rack to cool slightly. Serve warm with clotted cream and your favorite jam.
Enjoy these delightful, big fluffy vegetarian Irish scones with a touch of buttermilk – perfect for a cozy tea time treat!