In a large bowl, combine the flour and salt. Cut in the cold, cubed butter using a pastry cutter or your fingertips until the mixture resembles coarse crumbs.
Add the egg and gradually pour in ice-cold water, mixing with a fork until the dough just comes together. Knead briefly on a floured surface, form into a disk, wrap in plastic, and chill for 30 minutes.
Preheat your oven to 200°C (390°F). Lightly flour a clean surface and your rolling pin. Roll out the chilled dough to about 1/8 inch thickness.
Use a small round cutter or glass to cut out about 3-inch circles from the dough. Gather scraps, reroll, and continue until all dough is used.
In a skillet, cook the ground beef with the chopped onion over medium heat until browned and fragrant, about 5-7 minutes. Stir in smoked paprika, cumin, and lime juice, then let the mixture cool slightly.
Place a teaspoon of the filling in the center of each dough circle. Fold the dough over to form a half-moon shape and press the edges together.
Seal the edges tightly by pressing with the tines of a fork, ensuring no filling can escape during baking.
Beat the remaining egg and brush it lightly over the tops of the empanadas for a shiny, golden finish.
Arrange the empanadas on a lined baking sheet and bake for 20-25 minutes, turning once if needed, until they are golden brown and crispy.
Remove from the oven and let rest for 5 minutes on a wire rack to keep the crust crisp.
Serve warm, optionally with salsa or your favorite dipping sauce, and enjoy these flaky, flavorful mini empanadas.
