Since this dish involves a lot of components, it's easier on the cook of you do it in stages. Both the bean and beef mixtures can be made ahead of time. The flour for arepas is sold as masarepa or masa precocida.
1 lb. flank steak, cut into 2 or 3 pieces
5 to 6 cups beef broth
1 1/2 cups dried, soaked black beans
2 large onions, minced
4 garlic cloves, minced
2 red bell peppers, minced
1 1/2 tbsp. ground cumin
1 tsp. red wine vinegar
Kosher salt and freshly ground black pepper
1 can (14.5 oz.) diced tomatoes
1 1/2 tbsp. capers
2 cups arepa flour
1 ripe plantain, cut into 1/2-inch slices
4 oz. cotija cheese
1. In a medium saucepan, combine steak and broth (enough to cover meat). Bring to a boil, reduce to a simmer, coverm and cook until meat is tender, about 1 1/2 hours. Reserve broth and set steak aside to cool. When cool enough to handle, shred.
2. Drain and rinse beans. In a small saucepan, combine beans with water to cover by 1 to 2 inches. Bring to a boil, reduce to a simmer, partially cover, and cook until tender, 1 to 1 1/2 hours.
3. In a large skillet, heat 2 tbsp. oil over medium-high heat. Add onions, garlic, and bell peppers and cook until softened. Stir in cumin and cook 2 minutes.
4. Add one-third of sautéed onions and peppers to beans along with 1/2 cup reserved beef broth, the vinegar, and salt and black pepper to taste. Simmer, partially covered, for 20 minutes, then set aside and keep warm.
5. Add shredded beef to remaining onion and pepper mixture and cook, stirring, about 10 minutes. Add tomatoes and salt and pepper to taste. Cook until sauce thickens. Stir in capers. Set aside and keep warm.
6. Preheat the oven to 350ºF.
7. In a large bowl, stir together 2 cups warm water and 1 tsp. salt. Slowly stir in flour to make soft dough, adding water if it seems dry. Cover with plastic wrap and let rest 5 minutes. Knead dough until smooth, about 3 minutes. Shape into 12 oversized golf balls, then flatten into disks about 3 inches in diameter and 1/2 inch thick.
8. In a large skillet, heat 1/2 inch oil. Working in batches, fry arepas, turning, until crust forms, 4 minutes per side. Transfer to an ungreased baking sheet as you work. When all the arepas are fried, place in oven and bake for 20 minutes, or until arepas sound hollow when tapped.
9. In skillet, heat 1/2 inch oil. Add plantains and cook, turning, until lightly browned. Drain on paper towels. Sprinkle with salt.
10. To serve, slice arepas crosswise leaving hinge, scoop out insides and fill with beef, beans, and plantains; top with cheese.