In a mixing bowl, combine the flour and salt. Add the chilled, diced butter. Using your fingers or a pastry cutter, mix until the mixture resembles coarse crumbs.

Gradually add cold water, mixing until the dough comes together. Wrap it in plastic wrap and let it rest in the fridge for 30 minutes.

In a large skillet, heat a little oil over medium heat. Add the chopped onion, bell pepper, and minced garlic, and sauté until softened (about 5 minutes).

Add the ground beef, cumin, paprika, salt, and pepper. Cook until the beef is browned and fully cooked through, about 8-10 minutes. Let it cool slightly.

Preheat your oven to 400°F (200°C). Roll out the rested dough on a floured surface to about 1/8 inch thickness.

Use a round cutter or a glass to cut out circles of dough (about 4-5 inches in diameter).

Place about a tablespoon of the beef filling in the center of each circle. Fold the dough over to create a half-moon shape, pressing the edges to seal.

Place the assembled empanadas on a baking sheet lined with parchment paper. Brush the tops with the beaten egg for a beautiful golden finish.

Bake in the preheated oven for 25-30 minutes, or until golden brown and crispy.

Let the empanadas cool slightly before enjoying them warm. Serve with your favorite toppings!