Mix spinach, parsley, water, onions and tarragon in small saucepan. Bring to boil on medium-high heat. Reduce heat to low; cover. Simmer 1 min.; drain.
Place spinach mixture in blender or food processor.
Add remaining ingredients; cover. Blend until smooth.
Place in serving bowl; cover.
Refrigerate several hours or overnight.
Serve with assorted cut-up fresh vegetable dippers.