Roughly chop cucumber, bell pepper, chile, onion and garlic; put them in
blender (or vegetable juicer, if available) with the water and process thoroughly.
Strain, pressing well to extract all the juices.
Return strained liquid to blender with avocado flesh, cilantro leaves (leaving
a few for decoration), lime juice and salt. Process to puree, adjust seasoning.
Serve chilled, topped with a dollop of sour cream, lime quarters and kosher
salt. Accompany with small glasses of tequila, either to sip with lime and salt,
or to stir directly into the soup (optional).