- In a saucepan off the heat, combine the sugar, cornstarch and cinnamon. Add the apples and lemon juice. Bring to a boil and cook for about 3 minutes, stirring, until the apples have slightly softened. Cool and refrigerate until completely chilled.
- In the bowl of a food processor, combine the flour, sugar, baking powder and salt. Add the butter, eggs and water. Blend until the dough is smooth and forms a ball. With your hands, shape into a disc and refrigerate for about 30 minutes.
- In a bowl, combine the sugar and cinnamon. Set aside.
- Preheat the oil in the deep fryer to the highest temperature. Line a baking sheet with paper towels or double with a rack.
- On a floured work surface, roll out the dough to a 3-mm (1/8-inch) thickness. Cut into a 46 x 30-cm (18 X 12-inch) rectangle, then cut into 12 rectangles of 15 X 7.5-cm (6 x 3-inch).
- Spread about 20 ml (4 teaspoons) of filling at one end of each rectangle to within 1-cm (1/2-inch) of the edge. Brush the edges with the egg white and fold the dough over the apples to form squares. With a fork, press the edges to seal the dough.
- Fry about 4 turnovers at a time for 2 to 3 minutes or until they are golden brown on each side. Drain on the sheet. Sprinkle with cinnamon sugar. Serve hot, warm or cold.