Place ham bone in a large pot and fill with water. Bring to a boil and simmer for about an hour.
Peel and dice potatoes and ham. Chop onion.
Strain out the bones and meat from your stock.
Add potatoes and onion.
Bring to a boil and turn down heat. Simmer for approximately 15-20 minutes till potatoes are done.
Add ham just to heat it up. Check your seasonings. Add a little more salt or pepper.
Let the soup sit for about 1/2 an hour. Then add buttermilk.
There you go! A good old fashioned Mennonite borsch.