In a large mixing bowl, combine flour, cornmeal, and salt. Add cold butter pieces and work into the flour mixture until it resembles coarse crumbs.

Gradually add cold water, mixing until a smooth dough forms. Knead for 3-4 minutes, then cover and let rest for 20 minutes.

Heat olive oil in a large skillet over medium heat. Add diced onions and garlic, sauté until softened, about 3 minutes.

Add ground beef to the skillet, breaking it apart with a wooden spoon. Cook until browned, about 6-8 minutes.

Stir in diced potatoes, cumin, paprika, salt, and black pepper. Cook for 5 minutes until potatoes begin to soften.

Add tomato paste and a splash of water. Simmer for 8-10 minutes until potatoes are tender and mixture is thickened. Remove from heat and let cool completely.

Divide the dough into 12 equal portions. Roll each portion into a ball, then flatten into a 5-inch circle on a lightly floured surface.

Place 2-3 tablespoons of the beef filling in the center of each circle. Fold the dough over to create a half-moon shape.

Press the edges firmly to seal, then use a fork to crimp the edges decoratively.

Heat vegetable oil in a deep pot to 350°F. Fry empanadas in batches for 3-4 minutes per side until golden brown.

Remove with a slotted spoon and drain on paper towels. Serve hot with ají sauce.