Salvadoran Rice and Beans

Name: Salvadoran Rice and Beans
Cuisine: American, Latin American
Ingredients: 2 cups cooked white rice (preferably day old); 1 ½ cups cooked black beans or red beans (with a bit of the cooking liquid reserved); 1 medium onion, finely chopped; 1 green bell pepper, diced; 2 garlic cloves, minced; 2 tbsp vegetable oil or lard; 1 tsp ground cumin; ½ tsp paprika; Salt and black pepper, to taste; Fresh cilantro, chopped (optional, for garnish); Lime wedges (optional, for serving)