For the pernil: In a blender, combine the Worcestershire, guava paste, peppercorns, ginger, fennel seeds, cumin seeds, bay leaves, oregano, and garlic. Transfer the marinade to a Dutch oven or other large pot; stir in the malt beverage. Add the pork; cover and refrigerate 24 hours.
For the mango sauce: Meanwhile, heat the canola oil in a small saucepan over medium heat; add the garlic and jalapeno. Fry until lightly golden, about 2 minutes. With a slotted spoon, remove the garlic and jalapeno; transfer to a blender. Add the mango puree, olive oil, cilantro and papelon; blend until smooth. Refrigerate in an airtight container until ready to use.
When pork is ready to cook, preheat the oven to 400 degrees F. Bake until the meat shreds easily with a fork, about 4 hours. Shred the pork; reserve about 1 cup pork and freeze the remainder for another use.
For the arepas: Before serving, place 2 1/2 cups water in a medium bowl with 1 teaspoon salt and oil; slowly pour the cornmeal into the water. Knead together the cornmeal and water until blended and smooth. With wet hands, divide the dough into 6 even portions. Roll each dough portion into a ball; pat it into a 3 to 4-inch disk, about 1/2-inch thick.
Heat oil in a cast-iron skillet over medium heat; add the arepas. Cook the arepas until golden brown on both sides, turning once, about 10 minutes. Transfer the browned arepas to a baking sheet and bake until cooked through, 10 to 12 minutes.
To serve, partially split the hot arepas (not all the way around); remove some dough to make room for your filling. Fill the arepas with warmed pulled pork, 3 tomato slices, and a dollop of mango sauce. Serve immediately.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.