Place the masarepa in a large bowl. Add the sazon Goya and salt and stir to mix well. Add the water and oil and mix to form dough. Pat the dough into a ball and knead for 2 minutes or until smooth. Cover with plastic and set aside for 20 minutes.
Meanwhile, to make the filling, cook the potatoes in a pot with water for 20 minutes or until tender. Drain and gently mash the potatoes. Set aside.
Heat 1 tablespoon olive oil in a large, heavy skillet. Add the onion and cook over medium-low heat stirring frequently, for 5 minutes. Add the tomatoes, green onions, garlic, bell pepper, cilantro, salt and black pepper. Cook for about 15 minutes. Add the cooked potatoes and mix well.
In a medium bowl place the chopped egg, peanuts, potato and tomato mixture . Mix well to combine.
Break small portions of the dough, about 1 ½ tablespoons each one, and form each portion into a ball by rolling between the palms of your hands.
Place the balls of dough between two pieces of plastic and roll each out very thinly to form a circle. Remove the top plastic and place 1 tablespoon of the filling in the center of each.
Then using the plastic underneath, fold the dough over to enclose the filling, forming a half circle. Tightly seal the edges by crimping with the tines of a fork.
Fill a large pot with vegetable oil and heat over medium heat to 360°F.
Carefully place 3 or 4 empanadas at a time in the heated oil and fry for about 2 minutes until golden on all sides.
Using a slotted spoon transfer the empanadas to a plate lined with paper towels. Serve with hogao or aji on the side.