Sort the dried black beans and discard any stones or debris.

Soak the black beans overnight in water, ensuring they are covered by at least 2 inches.

Drain the soaked beans and rinse them thoroughly with cold water.

Set the rinsed beans aside.

In a large, heavy pot, heat olive oil over medium heat.

Add the diced onion to the pot and cook for about 15 minutes, or until softened and translucent.

Add the crushed garlic to the onion during the last 5 minutes of cooking.

Add the reserved black beans, water, bay leaves, dried chili (if using), cumin, and oregano to the pot.

Gently bruise the cilantro sprigs to release their aroma.

Tie the bruised cilantro sprigs together and add them to the pot along with 2 tablespoons of chopped parsley.

Bring the soup to a boil, then reduce the heat to medium-low.

Simmer the soup uncovered for about 1 1/2 hours, or until the beans are tender.

Skim off any foam that rises to the surface during simmering.

Discard the tied cilantro sprigs and bay leaves.

Remove about 2 cups of the soup from the pot, ensuring you get some garlic pieces.

Puree the removed soup using an immersion blender or in a regular blender.

Stir the pureed soup back into the main pot.

Season the soup with salt and pepper to taste.

Add the diced sweet red bell pepper, brown sugar, dry sherry, and lime juice to the soup.

Add 2 tablespoons of parsley and the chopped cilantro.

Cook the soup for an additional 30 minutes to allow the flavors to meld.

Serve the black bean soup hot in bowls over rice.

Garnish with a wedge of lime, a drizzle of sherry, and a dollop of sour cream.