In a large mixing bowl combine the flour, baking powder, sea salt, and baking soda.
Cut in the butter with a pastry cutter until the mixture resembles course crumbs.
Now add the sourdough starter and the buttermilk to the flour mixture and stir with a fork until the dough forms a ball.
You may need to adjust the flour or milk depending on how thin your starter is.
Turn the dough onto a well floured surface and knead 5-10 times. Don’t over knead the dough or it will become tough. And who wants tough biscuits?
Now gently roll or pat the dough out to 1/2 inch thickness.
Cut into rounds with a floured biscuit cutter. Or you could just cut it into squares if you wanted to.
Place the biscuits about 2 inches apart on a buttered baking sheet.
Now gently brush the tops with melted butter.
Bake these lovely discs of buttery amazingness at 425°F for 12-15 minutes or until they are a beautiful golden brown.