Toast the almonds in a small dry skillet over medium-high heat until fragrant, 3 to 5 minutes, stirring frequently; set aside.
Set aside 1 cup of the chopped cucumber for a garnish. Soak the bread in the water until soft, about 2 minutes. Place the soaked bread, the rest of the cucumber, the garlic, 1/4 cup of the scallion whites, the vinegar, lemon juice, 1/4 cup of the almonds, the salt, and oil in a food processor and process until the cucumbers are completely blended and the liquid and almonds are almost completely invisible, 1 to 2 minutes. Season with more salt and vinegar, if desired.
To serve, ladle 1 cup gazpacho into each serving bowl. Mound 1/4 cup of the reserved chopped cucumber, 1 tablespoon of the remaining scallion whites, 2 Tbs. of the grapes, and 1 tsp. of the almonds in the center of the soup and serve.