Yield: 6 servings.
3 large European cucumbers, washed, halved, and seeded
3 cups plain Greek yogurt
3 tablespoons fresh lemon juice
1 small shallot, chopped
2 garlic cloves
½ cup loosely packed fresh dill
¼ cup loosely packed flat-leaf parsley leaves
¼ cup loosely packed fresh arugula
3 tablespoons loosely packed tarragon leaves
¼ cup olive oil, plus more for drizzling
Freshly ground white pepper
½ red onion, finely chopped (for garnish)
Finely dice 1 cucumber, to measure 1 cup. Set aside. Coarsely chop the remaining cucumbers. In a blender, combine the coarsely chopped cucumber with the yogurt, lemon juice, shallot, garlic, dill, parsley, arugula, tarragon, and ¼ cup of olive oil. Blend on high until smooth. Season with salt and white pepper. Cover and refrigerate for at least 8 hours or overnight.
If needed, season the soup again with salt and pepper just before serving. Pour the soup into bowls. (If desired, chill the bowls in the refrigerator before serving soup.) Garnish with the finely diced cucumber and red onion. Drizzle each serving with olive oil.