In a small bowl, combine sourdough starter and buttermilk. Mix and let sit while you start the next step
In a large bowl, combine flour, baking powder, sugar, and salt
Using a cheese grater, grate the stick of butter into the flour mixture. Use your hands to combine and make crumbly
Pour the liquid sourdough mixture into the dry ingredients and combine
Turn out onto a lightly floured surface and form into a ball
Use a rolling pin to roll out the biscuit dough to about 1" thick
Use a biscuit cutter or circle cookie cutter to cut out your biscuits. Place on a baking sheet
Place baking sheet of biscuits into the freezer for a few minutes while you preheat your oven
Preheat oven to 425°F
Remove biscuits from freezer and bake in oven for 15-20 minutes. *each oven is different. Bake until golden brown on top
Serve and enjoy!