Heat oven to 450°F.
In a medium-size bowl or food processor, mix the flour, baking powder, and sea salt. Mix on low. Add or pulse in the cubed butter until the mixture forms coarse crumbs.
Add vinegar to the milk, then briskly mix (or pulse) liquids into the dry ingredients until the ball forms (if you are making buttermilk biscuits, do not add vinegar). Do not overmix!
Turn dough onto surface dusted with flour. With your hands, gently pat dough into a square and fold the dough over itself a few times (this yields fluffy biscuits). Pat dough until it is 1/2 inch thick. If you prefer to use a rolling pin, roll gently and continue to fold the dough. Use caution to not overwork, or press, dough too hard.
Cut with 2 1/2-inch round biscuit cutter. Place rounds on a cookie sheet lined with parchment paper.
Bake 8 to 10 minutes or until golden brown. Serve warm.
