Preheat oven to 450°F. Lightly grease baking sheet.
In medium bowl place all dry ingredients. Using a fork, cut in shortening until mixture is crumbly. Add milk and vinegar, stir just until fully combined.
For Rolled Biscuits: Place dough on lightly floured surface. Roll dough to 1-inch thickness and cut into desired shape. Place biscuits with edges touching onto prepared baking sheet. Bake 13-15 minutes or until lightly browned.
For Drop Biscuits: Divide dough into 9 parts, drop onto prepared baking sheet. Bake 12-14 minutes or until lightly browned.
Immediately brush hot biscuits with melted butter. Serve hot.