Lentil Bacon Soup with Frankfurters

Preparation

Preparation time: 15 min. 
Rinse the lentils thoroughly under cold water and let them drain.
Heat the oil in a large pan and cook the onion gently for 5 minutes.  Add the leek, carrot, celery, bacon, and bay leaves.
Add the lentils. Pour the water over them and bring slowly to a boil. 
Skim off any foam, partially cover the pan, and let the lentils simmer for 45-50 minutes until cooked.
Remove the bacon from the soup and cut it into pieces.
Add the bacon pieces, the parsley, and the sliced frankfurters to the soup.
Season with salt and pepper.
Let the soup simmer gently for 2-3 minutes, then remove the bay leaves.
Ladle the soup into bowls and serve sprinkled with parsley.