Saute leeks in hot oil in a Dutch oven until tender. Add zucchini and broth. Bring to a boil; cover, reduce heat, and simmer 8 to 10 minutes or until zucchini is tender. Remove from heat; cool slightly.
Process mixture in batches in a blender until smooth, stopping to scrape down sides.
Stir in half-and-half and next 3 ingredients. Chill at least 3 hours. Garnish, if desired.
I have been making this since it was first published in SL.......LOVE IT. Make it with the Shrimp Orzo Salad that was in the magazine. Makes the BEST lunch when you are having guests. I usually do a peach dessert to make it perfect for a summer day.