Put flour in bowl, then cut the butter into the flour like you are making a pie crust until the flour is in pea sized peices.
Add the milk and the apple cider vinegar. If the dough isn't quite wet enough add more milk but slowly until the dough is wet.
Mix it thoroughly.
Allow to soak overnight to 24 hours.
After soaking period add in baking soda, baking powder and sea salt.
Using your hands, fold the dough 10-15 times, squishing the dough down to mix the dry ingredients inches.
On a floured surface, roll the dough out until it is about an inch thick in a rectangular shape. Cut into 12 pieces. At this point you can freeze the dough also if you are making it well ahead of time.
Place cut peices onto an ungreased baking sheet and bake at 450 degrees for 8 to 10 minutes.