In a large mixing bowl, combine the flour and salt. Add the cubed butter and use your fingers or a pastry blender to mix until the mixture resembles coarse crumbs.

In a small bowl, whisk together the egg, cold water, and vinegar. Gradually add this mixture to the flour mixture, stirring until a dough forms. Knead lightly, wrap in plastic wrap, and refrigerate for 30 minutes.

Heat the olive oil in a skillet over medium heat. Add the ground beef and cook until browned, breaking it apart with a spatula.

Add the chopped onion, garlic, and bell pepper to the skillet. Cook until softened, about 5 minutes.

Season the mixture with cumin, smoked paprika, salt, and pepper. Stir well and cook for 2 more minutes. If using, stir in raisins and green olives. Remove from heat and let the filling cool completely.

Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.

Roll out the chilled dough on a floured surface until it is about 1/8-inch thick. Use a round cutter (about 4-5 inches in diameter) to cut out circles.

Place a spoonful of the cooled filling in the center of each dough circle. Fold the dough over to create a half-moon shape and press the edges together. Use a fork to crimp the edges and seal the empanadas.

Brush the tops of the empanadas with the beaten egg to create a golden crust.

Arrange the empanadas on the prepared baking sheet and bake for 20-25 minutes, or until golden brown.

Serve warm and enjoy!