To make the soup, heat the oil in a large saucepan over high heat until very hot. Add the onion and garlic and saute for about 2 minutes. Add the cumin and saute for 2 minutes longer. Add the Marsala and reduce until about 1/2 cup remains, about 4 minutes. Add the peppers and stock, decrease the heat to medium, and simmer for about 20 minutes. Add the cilantro and season, to taste, with salt and pepper.
Carefully puree the soup in a blender. Transfer the soup to a large bowl, cover, and refrigerate until well chilled, about 2 hours. (If the soup is too thick after chilling, thin it down with a bit more stock.)
Meanwhile, to prepare the salsa, combine the onion, garlic, chiles, and avocados in a bowl, and mix well. Add the lime juice, mix well, and season, to taste, with salt and pepper. Cover and refrigerate until you are ready to serve.
To serve, ladle the soup into bowls, and garnish with the salsa, creme fraiche, and a cilantro sprig.
Recipe courtesy of Caprial and John Pence, Caprial and John's Kitchen, Ten Speed Press, 2002