To make the pastry, mix the flour, salt and baking powder with the vegetable butter and butter. Cut it 2 knives until it mixture resembles oat flakes. Avoid using your hands. Add the iced water gradually until mixture starts to come together. Place in the refrigerator until the next day or for a minimum of 3 hours.
Preheat the oven to 400°F. To make the filling, in a saucepan over medium heat, add the oil and fry the onions until they become transparent. Add the meat and to cook it until golden. Season it with salt, pepper, and paprika. Mix well. Transfer the preparation to a plate and let it cool. Roll out pastry on lightly floured surface. Cut disks of approximately 3-4 inches with a glass or cutter. With a teaspoon put a small portion of the meat preparation in the center of each disk and add some egg and olives. Add some drops of water to the borders of the disk and foil the pasty in half covering the filling (turnover). Press down the borders with fingers to seal the turnover. Place them in previously greased and lightly floured baking sheet. Mix the yolk with the milk and "paint" the turnovers with a brush. Bake them for 20 minutes or until they look golden. Allow to cool. Serve dusted with confectioners sugar