Cook your choice of meat until just done and set aside. Cook the black beans and mash them into a purée; set aside. Finely dice the onion and set aside.

Sauté the onion, then add the cooked meat. Season with salt and pepper, then set aside.

Soften the masa with a little water and knead until you have a smooth dough for making tortillas. Brush with achiote paste.

Divide the dough into small balls and flatten them with a tortilla press. Fill each with a layer of black bean purée and the meat mixture, then fold and seal the edges. Set aside.

Heat the oil to 350°F (180°C). Fry the empanadas until golden, then drain on paper towels. Serve hot.