In a large pot, heat the oil and/or butter over medium-high heat. Add the onion, celery and carrots and sauté until soft, about 8 minutes. Add pork and marjoram; cook 1 minute. Add peas and water and bring to boil. Reduce heat to medium-low, partially cover the pot and simmer soup for an hour or so, until the vegetables are very tender.

Transfer hocks to bowl. Puree about half the soup in a blender (or using a hand-held immersion blender) and return it to the pot with the un-pureed soup. Cut the meat off the bones, discarding the thick layer of fat; dice the pork and return it to the pot. Season with salt and pepper and heat through.