Prepare a charcoal or gas grill for direct cooking over medium heat. Brush corn, tomato, and sweet peppers with olive oil. Grill vegetables for 8 to 12 minutes or until charred on all sides, turning occasionally and brushing with an additional 1 tablespoon olive oil. Remove from grill; cool.

Cut corn kernels from cobs; set aside ⅓ cup kernels for garnish. Chop tomato; remove steams and seeds from peppers. Peel and slice ½ cucumber. Combine remaining corn kernels, chopped tomato, peppers, and cucumber in a high-powered blender. Add olive oil, sherry vinegar, salt, and black pepper. Cover and blend until smooth. Chill before serving.

To serve, pour soup into serving bowls; top with reserved corn kernels and sliced cherry tomatoes, if desired.