Celery and Parsnip Soup with Green Onion-Dill Matzo Balls

Ingredients

6 tablespoons (3/4 stick) unsalted pareve margarine

9 cups thinly sliced celery stalks (about 2 bunches)

2 cups finely chopped peeled parsnips (about 12 ounces)

1 1/2 cups chopped green onions

1 large garlic clove, chopped

1 thin round of peeled fresh ginger

6 cups (or more) homemade chicken stock or canned low-salt broth