2 lb dried Navy beans or Great Northern beans
1 smoked pork shoulder, about 2 ½ lbs. (the meatier, the better)
8 Tbsp unsalted butter or margarine (1 stick)
4 large onions, peeled and roughly chopped
8 large celery stalks, chopped
8 cloves garlic, peeled and chopped
1 cup dry white wine
6 qt vegetable broth or stock
3 medium Yukon gold potatoes
1 cup chopped parsley
Kosher salt and ground white pepper, to taste

Soak the beans in water overnight. Make sure the beans are covered with a couple of inches of water as they can expand somewhat.  Drain the beans. In a heavy-bottomed soup pot, combine the vegetable stock, the drained beans and the ham hock. Bring to a boil, reduce heat to a simmer.  Simmer, covered, for 2 hours, occasionally skimming off any scum that forms on the surface.
In a separate saucepan, heat the butter or margarine over a low-to-medium heat.  Add the onion, celery and garlic to the butter and cook for 2-3 minutes or until the onion is slightly translucent, stirring more or less continuously. Add the wine and cook for another minute or two or until the wine seems to have reduced by about half.  Add the onion mixture and parsley  to the soup and simmer for another hour or until the beans are tender.
Peel and dice the potatoes, then boil in a separate pot until tender.  Drain and mash the potatoes (you do not need to add liquid or seasonings.)  (If using leftover mashed potatoes, the volume should be 2 c. )
Remove the pork shoulder from the soup. Pull the meat off the bone, chop it up and return the chopped meat to the soup. Stir in the mashed potatoes to thicken.  If necessary, add more stock or water to the soup to adjust the thickness.
Season to taste with Kosher salt and white pepper and serve. 

This recipe makes over a gallon of soup, but it freezes well.