Preheat oven to 450 degrees F. Line a baking sheet with parchment paper or a silicone baking mat. In small bowl or drinking glass, mix milk and vinegar. In a large bowl, combine flour, baking powder, salt, baking soda and sugar. Add cold butter and shortening using your fingers to work into the dry ingredients until it resembles coarse crumbs. Add the milk/vinegar mixture and stir using a rubber spatula until a soft dough forms. Working on a lightly floured surface, knead the dough 3-4 times until it comes together. Using a rolling pin, roll the dough into a 1 1/4-inch thick rectangle. Cut out 10-12 rounds using a 2 1/2-inch biscuit or cookie cutter. Place biscuits onto the prepared baking sheet; place in the freezer for 15 minutes. Remove biscuits from freezer and brush tops with egg wash. Place into oven and bake for 15-18 minutes, or until golden brown. Serve warm