1 cup chopped leeks (or onion if you perfer)
  1 Tbsp butter
  1 Tbsp. flour
  2 cups diced potatoes
  2 cups sorrel, packed
  1 pint chicken broth
  1 cup milk or cream
  tarragon, summer savory, marjoram, etc.
  Saute leeks in butter until limp and then stir in flour. Add salt and 
  pepper to taste.  Add broth and potatoes.  Bring to a boil and reduce heat 
  and simmer, covered, about 20  minutes until potatoes are tender.  Add 
  sorrel and herbs and cook about 5 minutes longer.  Cool slightly.
  
  Pour into food processor and blend until smooth (do not overfill
  processor, do in batches if necessary).  Return to pan and stir in
  cream and adjust seasonings.  Garnish with a chiffonade of the sorrel.
  We eat this hot the first meal and chilled for the left overs.