For the dough, whisk together flour and salt in a large bowl. Cut in the cold butter using a pastry blender or your fingertips until the mixture resembles coarse crumbs. Gradually add ice water, a tablespoon at a time, mixing until the dough just comes together. Do not overmix. Flatten into a disk, wrap in plastic wrap, and refrigerate for at least 30 minutes.
For the filling, heat a tablespoon of oil (not listed, assumed olive oil or neutral oil) in a large skillet over medium-high heat. Add the ground beef and cook, breaking it up with a spoon, until browned. Drain off any excess grease.
Add the chopped onion to the skillet with the beef and cook until softened, about 5 minutes. Stir in the frozen peas, cumin, paprika, cayenne pepper, salt, and black pepper. Cook for another 2-3 minutes until heated through.
Preheat your oven to 375°F (190°C). Line baking sheets with parchment paper.
On a lightly floured surface, roll out the chilled dough to about 1/8-inch thickness. Use a round cutter (about 5-6 inches in diameter) to cut out circles. Reroll scraps as needed.
Place about 2-3 tablespoons of the beef filling onto one half of each dough circle, leaving a border. Moisten the edges of the dough with water and fold the other half over the filling to create a half-moon shape. Crimp the edges with a fork to seal.
Place the empanadas on the prepared baking sheets. Brush the tops with the beaten egg wash.
Bake for 20-25 minutes, or until golden brown and puffed.