Special equipment: A 4 1/2-inch round cutter
For the empanada dough: Sift the flour and salt into a large bowl and work in the butter with your fingertips, breaking it up and rubbing gently until the mixture resembles coarse meal. Beat together the vinegar, 1/3 cup very cold water and 1 of the eggs in a small bowl and add it to the flour mixture a little at a time, incorporating it with your hands until combined.
Lightly flour a work surface; turn the dough out onto the work surface and knead gently with the heel of your hand a couple of times just to bring the dough together. Form into a flat square, wrap in plastic and chill for at least 1 hour.
For the picadillo: Heat the oil in a large saute pan over medium-high heat. Sprinkle the beef with salt and pepper and cook, stirring to break it up into small pieces, until browned and cooked through, about 3 minutes. Remove to a bowl using a slotted spoon and set aside, allowing the fat to remain in the pan. Add the cumin, garlic, onions and bell peppers and cook until soft and fragrant, 7 to 8 minutes. Add the meat back to the pan along with the white wine, and cook until the wine is reduced by half, about 2 minutes. Add the tomato sauce, raisins, olives, capers and bay leaf and continue to cook until all of the flavors have come together and the liquid is mostly absorbed, about 10 minutes. Add additional salt and pepper to taste and set aside to cool. Once cooled, drain off any excess liquid.
To assemble the empanadas: Position an oven rack in the center of the oven and preheat to 425 degrees F. Line 2 baking sheets with parchment paper.
On a lightly floured surface, roll the dough out to about 1/8 inch thick. Using a 4 1/2-inch round cutter, cut out 12 dough circles. Drop 1 heaping tablespoon of the filling onto each circle. Beat the remaining egg in a small bowl and brush the edges of the circles with the egg. Hold an empanada in one hand and use the thumb and forefinger of the other hand to bring the edges together; pinch the edges gently to seal. Starting at one edge, pinch the dough to extend it out slightly, then fold the pinched edge over to seal securely. Continue pinching and folding along the edge to create a rope effect. Fold the last bit of dough back onto itself to finish the seal. Place the empanada on the prepared baking sheet and brush the top with the beaten egg. Repeat with the remaining empanadas.
Bake until golden brown, 15 to 20 minutes. Serve hot or at room temperature.
This makes more than enough picadillo to fill the empanadas. The leftovers can be used for making papas rellenas, served over rice or frozen for your next batch of empanadas. You can also double the dough recipe to make a total of 24 empanadas with the single recipe of picadillo.