Line a large pot with water and add onion. Cook over medium high heat until onions are begining to be translucent, about 3 minutes. Add parnsips and celery and cook until celery turns bright green and starts to soften, about 3 minutes. Stir in shallot and garlic and cook for another two minutes. Add all remaining ingredients, cover and bring to a boil over high heat. Let boil for 2-3 minutes, then reduce to low and simmer 45-60 minutes. Jane's recipe called for using an immersion blender, which you can do here, but I transfered my soup to the blender in batches, pulsing to prevent overly pureeing the soup and making it too thin. Garnish with celery leaves or sliced green onions and fresh black pepper.