great northern beans are white beans that have a mild flavor.
in a medium size bowl, soak beans in 3 cups of water overnight.
drain the water and rinse beans.
in a large pot, brown onion, chicken, and ham in oil over medium to high heat for about 5 minutes.
add water, beans, and salt to pot. mix well.
bring pot to a boil and cook for 5 minutes.
lower heat and cook for about 1 hour. stir pot every 15 minutes.
add tomatoes and vinegar to pot. keep cooking over low heat for about 20 minutes. serve hot. 