For the dough: In a large bowl, whisk together flour and salt. Cut in the cold butter using 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. Form into a disk, wrap in plastic wrap, and refrigerate for at least 30 minutes.
For the filling: In a skillet, cook ground beef over medium heat until browned. Drain off any excess fat. Add chopped onion and cook until softened. Stir in minced garlic, cumin, chili powder, salt, and pepper. Cook for 1 minute more. Remove from heat and stir in the pre-cooked diced potatoes and chopped hard-boiled eggs.
Preheat your air fryer to 375°F (190°C).
Roll out the dough on a lightly floured surface to about 1/8-inch thickness. Cut out circles using a 5-6 inch round cutter.
Place about 2-3 tablespoons of filling onto one half of each dough circle. Fold the dough over the filling to create a half-moon shape. Crimp the edges with a fork to seal.
Brush the empanadas with the beaten egg wash.
Place the empanadas in the air fryer basket, ensuring not to overcrowd. Cook for 12-15 minutes, or until golden brown and crispy, flipping halfway through.