Sort beans, and rinse thoroughly. Combine beans and water to cover 2 inches above beans in a large Dutch oven; cover and let stand overnight. Add whole onion, tomato, bay leaf, and additional water, if necessary, to cover 1 inch above beans. Bring to a boil. Reduce heat; cover and simmer 2 hours or until beans are tender. Drain beans, reserving liquid. Add water to liquid to yield 3 cups. Pour liquid over beans, and set aside. Discard onion, tomato, and bay leaf.
Brown pork on all sides in 2 tablespoons hot olive oil in a large skillet. Reduce heat; cover and cook 15 minutes.
Add 2 additional tablespoons olive oil to skillet. Stir in chopped onion, ham, green pepper, garlic, and oregano. Cook, stirring constantly, until vegetables are tender. Stir in rice, salt, pepper, and hot sauce. Cook over low heat 10 minutes, stirring often.
Stir rice mixture into bean mixture in a large Dutch oven. Bring to a boil. Cover and bake at 325° for 30 minutes or until rice is tender.
Heat garlic powder and remaining olive oil in a small skillet. Stir into bean mixture. Add lemon juice and vermouth, toss lightly. Spoon mixture into a 3- quart serving dish. Garnish with parsley sprigs, if desired.