Halve the onion. Heat a large pot without fat. Place the onion halves in the pot with the cut surface facing down and fry until the cut surface is dark brown. Put the spices in a tea infuser or tea strainer.
Rinse the meat under cold water and put it into the pot. Add about 2 litres of water, onion, some salt and spices. Bring the soup to the boil, simmer for about 2 hours at low heat. Skim and degrease soup regularly.
Peel, wash and dice the celery, potatoes and carrots. Add vegetables and potatoes to the soup about 30 minutes before the end of cooking. For the spaetzle, mix flour, eggs, 1/2 teaspoon salt and approx. 75 ml water to a smooth thick dough and beat with your hands until the dough gets bubbles.
Press the dough in portions through a spaetzle press into boiling salted water. When the spaetzle float on the surface, remove with a skimmer. Remove the meat from the soup, let it cool down a bit and cut it into small cubes.
Wash parsley, shake dry and finely chop the leaves of 4 stems. Remove spices and onion halves. Add spaetzle, chopped parsley and meat to the soup. Garnish soup with parsley leaves.