In a large bowl, whisk together flour and salt. Cut in the cold butter with a pastry blender or your fingertips until the mixture resembles coarse crumbs.

Gradually add ice water, 1 tablespoon at a time, mixing until the dough just comes together. Do not overmix.

Gather the dough into a ball, flatten it into a disc, wrap it in plastic wrap, and refrigerate for at least 30 minutes.

In a large skillet, cook the ground beef over medium heat until browned. Drain off any excess grease.

Add the chopped onion and minced garlic to the skillet and cook until softened, about 5 minutes.

Stir in the diced tomatoes, chopped olives, cumin, oregano, cayenne pepper, salt, and black pepper. Cook for another 5-7 minutes, or until the sauce has thickened slightly.

Remove from heat and let the filling cool completely.

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

On a lightly floured surface, roll out the chilled dough to about 1/8-inch thickness. Use a 5-6 inch round cutter to cut out circles.

Place about 2-3 tablespoons of the cooled beef filling onto one half of each dough circle. Moisten the edges of the dough with water and fold the other half over to create a half-moon shape.

Crimp the edges with a fork to seal. Cut a small slit in the top of each empanada to allow steam to escape.

Whisk together the egg and water for the egg wash. Brush the tops of the empanadas with the egg wash.

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

Let cool slightly before serving.