You need:

1 lb potatoes, 2 carrots, 1/4 celery root, 1 leek, 1 large onion, 2 Tbs oil, 5 cups broth or water, salt, peper, marjoram, celery leaves and basil leaves.
 

Peel and wash the potatoes and cut them in little cubes, together with the leek, carrots and celery root. Chop the onion and saute it in the oil in a deeo pot until light yellow. Add the vegetables, mix, add the broth or water, and simmer for 30 minutes. 10 minutes before the end of cooking time, season the soup with salt, pepper and the finely chopped herbs.
 

If the soup is too thick, add some more broth. Optional add 1 Tbs sour cream!