Beef Empanadas

Sift flour with salt into a large bowl and blend in butter with your fingertips or a pastry blender until mixture resembles coarse meal with some (roughly pea-size) butter lumps. Beat together egg, water, and vinegar in a small bowl with a fork. Add to flour mixture, stirring with fork until just incorporated. (Mixture will look shaggy.) Turn out mixture onto a lightly floured surface and gather together, then knead gently with heel of your hand once or twice, just enough to bring dough together. Form dough into two flat rectangles and chill them, each wrapped in plastic wrap, at least 1 hour. Dough can be chilled up to 6 hours total. Cook onion in olive oil in a heavy medium skillet over medium heat, stirring frequently, until softened. Add garlic, cumin, and oregano and cook, stirring, 1 minute. Stir in beef and cook, breaking up lumps with a fork, until no longer pink, about 4 minutes. Add raisins, olives, 1/2 teaspoon salt, 1/4 teaspoon pepper, and tomatoes with reserved juice, then cook, stirring occasionally, until liquid is reduced but mixture is still moist, about 5 minutes. Stir in hard boiled egg and spread on a plate to cool. Lay a large sheet of plastic wrap on a dampened work surface (to help keep plastic in place), then roll out an empanada disk on plastic wrap to measure about 6 inches. Place 3 tablespoons meat mixture on disk. Moisten edges of disk with water and fold over to form a semicircle, then crimp with a fork. Make more empanadas in same manner. Put oven racks in upper and lower thirds of oven and preheat oven to 400F. Lightly brush empanadas with some of egg wash and bake in upper and lower thirds of oven, switching position of sheets halfway through baking, until golden, about 25 minutes. Transfer empanadas to a rack to cool at least 5 minutes. Serve warm or at room temperature.