Avocado Soup With Marinated Shrimp

3 large avocados, cut into chunks 
2 cans (14 oz) vegetable broth 
¼ tsp ground red pepper 
1 tsp salt, divided 
½ cup buttermilk 
4 tbs fresh lemon juice, divided 
¼ cup off dry white wine (optional) 
½ lb medium size peeled, cooked shrimp 
1 tbs olive oil 
1 tsp lemon zest 
garnish chopped fresh chives 

Process first 3 ingredients and ¼ tsp salt in a blender until smooth, stopping to scrape down sides. Transfer avocado mixture to a bowl, stir in buttermilk, 3 tbs lemon juice, and, if desired, wine until smooth. Place plastic wrap directly on soup, and chill at least 1 hour or upto 4 hours. During last 15 minutes of chill time for avocado mixture, combine shrimp, olive oil, lemon zest, and remaining 1 tbs lemon juice and ¾ tsp salt, and let stand 15 minutes. Ladle soup into small bowls, and top each with shrimp. Garnish, if desired. Serves 8-10.