Heat fat in a large skillet and add carrot, 1 onion, leeks and celery. Saute 5 mins. Add water and bring to a boil. Season with salt and pepper.
Add peas and bacon; cook slowly, covered, for about 1 hour, or until peas are cooked. Meanwhile, saute remaining onion in butter until tender. Add thyme and marjoram and mix into soup.
To serve, take out bacon and chop or slice; return bacon to soup. Serves 6 to 8.
Notes: A specialty soup of Berlin is one made with yellow dried peas and bacon, to which sliced sausages, such as Bockwurst, are often added.