Combine flour, salt, baking powder, baking soda and sugar in a large mixing bowl.
Grate butter and add to flour mixture.
Work the butter into the flour until you have a crumbly texture
Pour 1 cup of active sourdough starter and 1 and 1/2 cup of buttermilk (at room temperature) into the flour mixture.
Gently stir until a dough forms. If the mixture seems a bit dry, you can add a touch more buttermilk, but be careful not to over mix.
Turn your dough out onto a lightly floured surface and knead it gently until it comes together, making sure not to overwork it
Roll your dough out to a thickness of about 1/2 to 3/4 inches.
Using a biscuit cutter or a floured glass, cut out your biscuits.
Place them on a baking sheet lined with parchment paper and allow them to rise for 30 minutes to an hour.
Place the baking sheet with the unbaked biscuits in the freezer until they're firm.
Once they're solid, transfer them to an airtight container or freezer bags.
When you are ready to bake the biscuits, place on a baking sheet or cast iron skillet and bake at 425 degrees for 20-25 minutes or until golden brown.