Gather the ingredients.
In a blender, combine the coarsely chopped cucumber with the yogurt, lemon juice, shallot, garlic, dill, parsley, tarragon and the ¼ cup of olive oil. Blend until smooth. Season with salt and white pepper, cover, and refrigerate for at least 8 hours or overnight.
Season the soup again just before serving. Pour the soup into bowls. Garnish with the finely diced cucumber, red onion, and a drizzle of olive oil and serve.