Add onions and saute for 8 minutes, until they begin to brown.
Add garlic and saute for one minute more.
Add zucchini and saute for 1-2 minutes.
Add chicken broth, making sure to submerge all of the zucchini in the broth. Cover and bring to a boil. Reduce heat to medium low and let simmer for 10 minutes.
Remove from heat and allow to cool for about an hour.
Add cilantro, cream, cayenne and salt and pepper to taste.
Working in batches, puree the soup in a food processor. Transfer to a large storage vessel and chill in refrigerator.
Meanwhile, mix together cream, cilantro and sour cream and chill in refrigerator for 3-4 hours.
Add shrimp to marinade ingredients and let sit for 15-20 minutes.
Assemble shrimp on skewers and grill on medium high heat, 2-3 per side.
Let cool, chop the shrimp, squeeze a little extra lime over the shrimp and chill in the refrigerator.
Using a half cup label, spoon the soup into serving bowls, top with a dallop of sour cream and grilled shrimp.
Recipe by Weekend Table at https://weekendtable.com/2013/09/15/chilled-zucchini-soup-shrimp/