In a large bowl, dissolve yeast in warm water. Add milk, oil, sugar, egg and 2 cups flour. Beat until smooth. Stir in enough remaining flour to form a soft dough (dough will be sticky). Do not knead. Cover and refrigerate overnight. , Punch down dough. Turn onto a floured surface; roll into a 16x12-in. rectangle. Cut into 2-in. squares. , In a deep cast-iron or electric skillet, heat 1 inch oil to 375°. Fry squares, in batches, until golden brown on both sides. Drain on paper towels. Roll warm beignets in confectioners' sugar.