1 lb. dried white navy beans, sorted of debris and rinsed
1 (about 1-lb.) ham bone or uncured ham hock
2 1/2 qts. water
1 large russet potato (about 8 oz.)
3 cups chopped celery (about 6 stalks)
3 cups chopped yellow onion (about 3 medium onions)
1 garlic clove, minced
3 tsp. kosher salt
3/4 tsp. black pepper
1/4 cup chopped fresh flat-leaf parsley
Place beans in a Dutch oven; add water to cover, and soak 8 hours or overnight. Drain beans. Return to Dutch oven.
Add ham bone and water. Cover and bring to a boil over high; reduce heat to medium-low, and simmer 1 hour.
Rinse potato; pierce with a fork, and wrap potato in a paper towel. Microwave on HIGH until tender, about 4 to 5 minutes; peel and mash potato.
Stir potato, celery, onion, garlic, salt, and pepper into bean mixture; simmer over medium-low until beans are tender, about 1 hour.
Remove ham bone from Dutch oven, and let stand until cool enough to handle, about 20 minutes. Remove and discard bone and fat; dice meat, and stir into bean mixture. Top each serving with chopped parsley.