Parsnip-Celery Soup

Peel the onion, chop it finely, and sauté it in a pot with oil. Peel the potato, celery, and parsnip, cut them into large pieces, add them to the pot, and fill with vegetable broth. Let it cook for 20 minutes. Afterward, finely puree the mixture, season with black pepper, herb salt, and adjust the taste with vegetable broth if necessary.
Serve the soup in a bowl and garnish with fresh cress.