Prepare the beans: In a 5-quart pot, combine beans, bell pepper, onion, and 5 cups water. Let stand at room temperature for 3 hours or overnight.
Bring to a boil over high heat. Reduce to a simmer, cover, and cook until beans are tender, 45 minutes to 1 hour, adding more water if necessary to cover beans. Strain, reserving cooking liquid. If less than 3 cups of reserved cooking liquid add water to com to three 3 cups. Discard pepper and onion.
Make the sofrito: In same pot (rinsed and dried), cook pork over medium heat until lightly browned. Transfer pork to bowl. Add oil to pot and heat over medium-low heat. Add onion, bell pepper, and garlic. Cook stirring occasionally, until onion is tender, about 10 minutes.
Stir in beans, reserved cooking liquid, sherry, salt, oregano, black pepper, and bay leaf Bring to a boil. Stir in rice and return to boil. Reduce heat, cover, and simmer gently about 15 minutes. (Rice should be somewhat hard and dry at this point. It will finish cooking inside turkey.) Discard bay leaf and let cool before stuffing turkey.