Preheat the oven to 220C | Gas Mark 7. Line a baking tray with baking parchment and set aside.
Place the flour, baking powder, and salt in a large mixing bowl and stir to combine. Work the margarine into the flour mixture until crumbly.
Add the sourdough starter and mix using a wooden spoon to form a dough.
Turn the dough out onto a lightly floured surface and gently pat it until 1 inch thick.
Using a biscut cutter or a mug, cut out 6 rounds.
Place onto the prepared baking sheet and bake in the middle of the oven for 20 minutes until golden.
Best served warm with a generous dollop of jam.
