Make the filling: Place the beef, bay leaves, 1 tablespoon salt and water to cover in a saucepan and bring to a boil over medium heat. Reduce to a simmer, cover and cook until the meat is almost falling apart, about 1 hour 30 minutes. Transfer the meat to a bowl and shred with a fork; cool. Reserve the broth.
Heat the olive oil in a large skillet over medium-high heat. Add the onion, bell pepper, garlic and shallot; cook until the onion is translucent, about 3 minutes. Stir in the scallion, paprika, sazon completa, oregano, cumin and 1/4 teaspoon pepper. Add the beef and 1 cup of the reserved broth and cook over medium heat until thick, about 10 minutes. Season with salt.
Make the dough: Mix 3 1/2 cups hot water, the sugar, vegetable oil, butter and salt in a medium bowl until the butter melts. Stir in the cornmeal and flour until a soft dough forms, then knead on a clean surface until the dough comes together. Shape into 12 balls, using about 1/2 cup dough for each.
One at a time, sprinkle each dough ball with water, place between two pieces of lightly oiled heavy-duty plastic wrap (a cut resealable bag works well) and roll into a 7-inch circle. Remove the top sheet of plastic and place 2 to 3 tablespoons filling in the center of the dough. Use the bottom piece of
plastic to fold the dough in half over the filling and press to seal. Trim into a half-moon shape with a knife or press down with the round edge of a bowl. Remove the plastic and place the empanada on a parchment-lined baking sheet.
Preheat the oven to 300 degrees F. Heat 1 inch of vegetable oil in a large skillet until a deep-fry thermometer registers 365 degrees F. Fry the empanadas in batches until golden, about 4 minutes per side. Transfer to a paper-towel-lined baking sheet; keep warm in the oven.
Make the sauce: Combine the cilantro, olive oil, avocado, bell pepper, scallion, vinegar and garlic in a blender. Add 1 teaspoon salt and 2 teaspoons pepper and puree until smooth. Thin out the sauce with up to 1/4 cup water and serve with the empanadas.