Bring water to boil in large saucepan.
Meanwhile cut asparagus into 2-inch lengths and reserve tips.
Add tips to water and boil 45 seconds or until bright green and crisp tender.
Drain and rinse in cold water and drain again. Wrap and refrigerate for garnish.
Put chicken broth, asparagus pieces, carrots, onion, celery, garlic, tarragon and salt into same saucepan. Bring to boil, reduce heat, cover and simmer 30-35 minutes until veggies are very tender. Remove from heat.
When cool enough to handle, process in batches in blender (or with hand blender) until smooth.
Return to saucepan, stir in milk and half and half. Heat until simmering. Remove from heat and stir in lemon juice.
Garnish with reserved asparagus tips.