Green Gazpacho

Name: Green Gazpacho
Ingredients: 4 cups roughly chopped green heirloom tomatoes, such as Green Zebra; 2 white bread slices (about 3 oz.); ¼ cup extra-virgin olive oil; 2 teaspoons red wine vinegar; 1 teaspoon kosher salt; ¼ teaspoon cayenne pepper; 2 cups finely chopped peeled cucumber, divided; 1 pint multicolored heirloom cherry tomatoes, halved; ¼ cup sour cream