Finely chop ¼ of the cucumber and reserve for garnish.
Peel the remaining cucumber, cut into chunks, and transfer to a blender. Add the tomatoes, peppers, onion, garlic, cilantro, vinegar, olive oil, salt, and pepper. Blend until smooth. Season to taste and chill for at least 2 hours.
Serve the soup with the reserved diced cucumber, fresh herbs, drizzles of olive oil, and freshly ground black pepper.