Step 1: Prepare the dough by mixing the flour and salt in a large bowl. Cut in the cold butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs.
Step 2: Whisk the egg and water together, then gradually add to the flour mixture. Knead gently on a floured surface until a smooth dough forms. Wrap in plastic and refrigerate for 30 minutes.
Step 3: In a large skillet over medium heat, sauté the onions and garlic until translucent and fragrant.
Step 4: Add the ground beef to the skillet, breaking it up with a spoon. Cook until browned. Drain any excess grease.
Step 5: Stir in the cumin, paprika, oregano, salt, and pepper. Allow the mixture to cool completely before adding the olives and optional hard-boiled eggs.
Step 6: Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.
Step 7: Roll out the dough to 1/8-inch thickness and cut out 5-inch circles using a round cutter or a small plate as a guide.
Step 8: Place 2 tablespoons of filling in the center of each circle. Fold the dough over to create a half-moon shape.
Step 9: Seal the edges by pressing with a fork or using the traditional ‘repulgue’ braiding technique.
Step 10: Place the empanadas on the baking sheet and brush the tops with a whisked egg wash for a golden finish.
Step 11: Bake for 20-25 minutes or until the pastry is golden brown and crisp.
Step 12: Let them cool for 5 minutes before serving with your favorite dipping sauce.