The night before you want to make the biscuits, add the flour and olive oil in a mixing bowl and mix until the dough appears crumbly.
Add the sourdough starter and milk. Mix just until combined and no dry bits of flour remain.
Cover and let ferment on the counter at room temperature for 8-24 hours.
When ready to make the biscuits, preheat the oven to 425 degrees F.
Using your fingertips, make dimples in the top of the dough.
In a small bowl, combine the salt, baking soda, and baking powder.
Pour this salt mixture over the dimpled dough.
Fold the dough several times to incorporate the salt mixture into the dough.
Place the dough onto a work surface.
Roll out the dough into a rectangle and fold the dough over itself from each side and form into another ball.
Repeat this rolling out and folding the dough 3-4 times. This builds layers in the biscuits.
After the final rolling and folding of the dough, roll out the dough into a rectangle that is approximately 1-1 1/2 inch thick.
Cut out the biscuits with a biscuit cutter or mason jar ring.
Place the biscuits onto the baking sheet, baking stone, or cast iron skillet.
Bake in the preheated oven for 10-12 minutes or until lightly golden brown.