Soaking the Beans: The night before, place the black beans in a large container and cover them with plenty of water. Let them soak for at least 8 hours. This process will soften the beans and reduce cooking time. Do not discard the soaking water, as it helps preserve the dark color of the beans.

Cooking the Beans: In a large pot, add the soaked beans and cover them with chicken broth. If needed, add more water to ensure the beans are fully submerged. Bring to a boil over high heat, then reduce the heat and simmer, covered, for about 90 minutes or until the beans are tender.

Preparing the Sofrito: While the beans cook, heat the oil in a large pan over medium heat. Add the chopped onion and sauté until translucent, about 5-7 minutes. Add the crushed garlic, red bell pepper, and chopped ají dulce. Sauté for another 5 minutes until the vegetables are soft and fragrant.

Adding Spices: Stir the ground cumin into the sofrito and cook for 1 more minute, mixing well so the flavors combine. Season with salt and pepper to taste.

Combining Ingredients: Once the beans are tender, add the sofrito to the pot and mix well. Simmer over low heat for 15 more minutes to allow the flavors to meld.

Adding Culantro: Just before serving, stir the chopped culantro into the soup. Let it cook for a few more minutes to release its aroma and flavor.

Serving: Serve the soup hot in individual bowls. You can pair it with white rice or fried plantains if desired.