Sift flour, salt, baking soda and baking powder into a large bowl. Add cold butter and cut it into the flour mixture. Add the sourdough starter and mix until the mixture turns into a dough.

Turn the dough out on to a lightly floured board and knead the dough a few times until it becomes smooth and elastic.

Pat the dough into a 3/4 inch high round. Use a biscuit cutter to cut the dough into eight biscuits.

Bake in a 425 degree F. oven for 12-15 minutes until slightly brown.