Asparagus Soup

2 cups water
1 stalk celery
1 (19 ounce) can white navy beans
1 1/2 lbs asparagus
1/2 teaspoon fennel seeds
1/4 teaspoon celery seeds
1 teaspoon dried dill or 1 tablespoon fresh dill weed
1/2 teaspoon salt
1/2 teaspoon green peppercorns, lightly crushed
1 cup light cream

Wash and cut up the celery and put it in a large pot with the water and the canned beans, including the packing liquid from the beans. Heat to a simmer.
Wash the asparagus, and snap off both the tough ends and the tips. Grind the spices and add them to the soup. Add the asparagus stalks and ends to the soup and simmer until quite tender; about 10 minutes. Reserve the tips.
Remove the tough stem ends from the soup and discard. Puree the soup thoroughly in a blender. The soup may be made ahead up to this point; it should keep in the fridge for 24 hours.
To serve, add the cream (if using) and reheat the soup gently. Steam the reserved tips separately until tender.
Serve the soup garnished with the steamed tips.