Finely dice the veggies and greens because these vegetables and greens lend a rich savory fragrance and flavor to German broths and soups.
Rinse peas and soak in water to cover overnight. Put in a 4-quart pot with 2 quarts water, using whatever is left of soaking water if you wish, and adding additional amounts, if necessary. Add ham and bring to a boil. Cover, reduce heat and simmer 1 hour.
Heat butter or bacon fat in skillet; add diced vegetables and saute slowly until a deep golden color. Sprinkle with flour and stir until it is absorbed and browned.
Add flour-vegetable mixture to soup along with potatoes, marjoram, thyme, salt and pepper. Simmer, covered, for 1 hour, or until peas are soft enough to eat, but not entirely dissolved. They should retain some of their shape. Do not strain or puree. Remove ham or bacon and cut into small pieces and return to soup. Discard ham bone. (If you want you can use the bacon or smoked sausages by adding them and heating them in the soup before serving.)