To make the filling: In a large skillet, heat the oil. Add the onions, bell pepper, garlic, achiote, cumin and cook for about 6 minutes over medium heat.
Add the beef and cooked potatoes, and cook for about 7 minutes. Add the broth, season with salt and cook until meat is cooked through.
To make the dough: Place the flour and salt in a food processor.
Add the butter, and water until a dough forms.
Form a ball, cover with plastic wrap and place in the refrigerator for about 30 minutes.
On a lightly floured surface, roll out the dough into a thin rectangle. Cut out round disc shapes with a round cutter or a small plate.
Fill empanada discs with beef mixture. Brush the edges with egg and close the filling by pressing the edges together to form a half moon.
Preheat oil in a deep pot to 375 degrees F. Fry the empanadas in the oil for about 3 minutes on each side. Remove from the oil and drain on paper towels.