Season the shrimp with salt and pepper. In a large skillet, melt the butter over medium heat. Add the shrimp and cook, turning once, until opaque, about 45 seconds per side. Using a slotted spoon, transfer the shrimp to a plate. Add the cucumber, garlic and lemon peel to the skillet and cook, stirring occasionally, until the cucumber is almost translucent, about 8 minutes.
Using a food processor, puree the cucumber mixture, tomatoes with their juice and 1/2 cup water until smooth. Transfer to a large container and season with salt and pepper. Refrigerate the soup and shrimp separately for 1 hour. To serve, divide the soup among 4 bowls and float 4 shrimp in each. Pass bread around for dunking.