cold celery soup

This is a variation of PMC's soup algorithm, chilled for summer.

Sauté a thinly sliced medium onion in a few tbsp butter until the onion is soft and translucent. Add one whole bunch of celery, chopped and soaked (to remove sand and dirt), and enough diluted chicken broth (home-made or canned) to cover. Simmer for about 30 min. Blend until smooth in a blender, in a food processor, or in the pot with an immersion blender. Taste and adjust salt if necessary. Chill.

When cold, if you wish, mix in a small amount of cream or half-and-half for color and "body"; it's not necessary.