Asparagus Soup

Serves 6-8
2    tsp olive oil
1    small leek
1    small onion
2    medium russet potatoes peeled and chopped
2    pounds Asparagus
6    cups or more of chicken stock
¼   teaspoon cayenne pepper
1    tsp fresh lemon juice 
½   cup heavy cream
      salt and pepper to taste
      zest of one lemon

1.  In a large saucepan on medium heat, heat olive oil and saute leeks and onions for 3 minutes.  Add potatoes and Asparagus stalks and saute for 5 minutes.
2.  Add chicken stock and cayenne pepper and simmer until potatoes are tender, about 15 minutes. Cool slightly.
3.  In a seperate pan, steam Asparagus tips for 2 minutes.  Set aside.
4.  Working in batches, puree cooled soup in a blender or a food processor, or puree in the saucpan with an electric handheld blender.  Return soup to pan, stir in  lemon juice and cream, and add salt and pepper to taste.  Simmer for 5 minutes, adding more stock if a thinner soup is desired.  Add Asparagus tips and serve garnished with lemon zest.