2 slices white sandwich bread
1 cup water
1 1/2 pounds English cucumbers (about 2 small)
1 cup seedless green grapes, plus more for garnish
1/3 cup blanched, slivered almonds
1/3 cup extra-virgin olive oil, plus more for drizzling
2 cloves garlic, coarsely chopped
2 teaspoons sherry vinegar, plus more as needed
1 teaspoon fine salt
Finely chopped fresh chives, for garnish
Trim the crusts from the bread and cut the bread into 1-inch cubes. Place the cubes in a small bowl, mix in the water, and set aside to soak for 5 minutes.
Meanwhile, peel the cucumbers. Cut into large chunks and place in a blender. Add the 1 cup grapes, almonds, 1/3 cup oil, garlic, 2 teaspoons vinegar, and salt. When the bread is ready, add it and any remaining soaking liquid to the blender. Blend on high speed until very smooth, scraping down the sides of the blender jar as needed, about 2 minutes total.
Cover and refrigerate in the blender jar if it can fit, or transfer to a bowl or airtight container. Refrigerate until chilled and the flavors meld, about 2 hours.
Taste and season with more vinegar as needed. Pour or ladle into serving bowls and top with the chives, sliced green grapes, and a drizzle of olive oil.