Combine black beans and 6 cups cold water in a deep bowl and let soak overnight or 12 hours. Drain beans and rinse.
Heat oil in a large heavy-bottomed soup pot over medium-high heat. Add garlic and onion and cook, stirring often until starting to soften and brown, 4 to 6 minutes. Stir in Italian seasoning, pepper, and chipotle and cook, stirring until fragrant, 30 to 60 seconds. Add sherry, and cook, stirring occasionally until almost compleltly evaporated, 1 to 3 minutes. Add the drained beans, red bell pepper, ham hock and 8 cups cold water. Increase heat to high and bring to a boil. Reduce heat to maintain a gentle simmer, about medium-low, and cook until the beans are completely tender and falling apart, 1 ½ to 2 hours.
Remove ham hock. Puree the soup in batches. Return soup to the pot and stir in salt. Remove the ham from the bone, shred meat and discard any fat. Stir the ham into the soup, adjust salt if desired. Ladle soup into bowls top with scallion greens. Float 1 teaspoon vinegar on top of each serving.