Add the flour, sugar, baking powder, cream of tartar, and salt to a bowl. Stir to combine.
Add the butter to the dry ingredients. Cut in the butter using a pastry cutter or your hands.
Add the sour milk combo (vinegar and milk) to the dry ingredients. Mix until if forms a ball.
Using a biscuit cutter, cut out biscuits.
Place the cut biscuits on a parchment lined baking sheet.