How to Make It
Preheat the oven to 375°. On a large piece of foil, drizzle the beets with olive oil and season with salt; wrap tightly and bake for 1 hour, until tender. Let the beets cool slightly, then rub off the skins with a paper towel. Cut one beet into 1/4-inch dice and reserve for garnish.
Chop the remaining beet and transfer to a large glass bowl. Add the tomatoes, bread, pepper, chopped cucumber, berries, shallot, vinegar, garlic and 1/4 cup of the oil. Stir in a generous pinch of salt and let stand at room temperature, stirring, until the tomatoes release their juices and the bread is very soft, 30 minutes. Stir in 2 cups of water.
Working in batches, ladle the mixture into a blender and puree until very smooth. Strain the soup through a coarse sieve into a large bowl or pitcher. Cover and refrigerate until well chilled, at least 2 hours.
Whisk the remaining 1/4 cup of oil into the soup; season with salt. Ladle the soup into bowls. Garnish with mint, the diced beet and sliced cucumber, drizzle with oil and serve.