Combine ham bone, broth, and two cups water in a large sauce pot over medium-high heat. Bring to a boil, reduce heat to medium-low, and simmer 30 minutes or until liquid has reduced by half to three cups. Strain. 

Heat oil in a Dutch oven over medium-high heat. Add onion, bell pepper, and garlic; sauté five minutes. Add ham; sauté three minutes. Add collard greens, reserved ham broth, vinegar, salt, and hot sauce; bring to a boil, cover with lid, reduce heat to low and simmer one and a half hours, stirring often and adding water as needed. Taste; adjust seasoning if necessary.