Begin by soaking the black beans overnight in plenty of water, or use the quick-boil method by bringing them to a rapid boil for 2 minutes, then letting them sit covered for 1 hour. Drain and rinse before cooking.

In a large pot, combine the soaked beans with fresh water, bay leaves, bacon, and sausage. Bring to a gentle boil, then reduce the heat to low. Simmer uncovered for about 1½ to 2 hours, or until the beans are very tender and the broth has turned rich and dark. Skim the surface occasionally to remove any foam.

Once the beans are soft, remove the bacon and sausage from the pot. Let them cool slightly, then chop them into small, bite-sized pieces. In a separate skillet, heat olive oil over medium heat. Add the chopped onion and sauté until translucent and fragrant, about 5 minutes. Stir in the minced garlic and cook for another 30 seconds, allowing its aroma to bloom. Add the chopped bacon and sausage back into the skillet, tossing everything together so the flavors meld.

Transfer this mixture back to the pot with the beans. For a thicker texture, use an immersion blender to puree part of the soup until smooth, or remove a few cups of beans, mash them, and return them to the pot. Stir well and let the soup simmer for another 10 minutes to combine all the flavors.

Season generously with salt and black pepper to taste. Serve the soup hot, ladled into bowls, and garnish with a sprinkle of chopped cilantro or green onions for a burst of freshness and color.