Peel the cucumbers and cut them into cubes. Slice the white part of the scallion into thin strips. Squeeze the juice from the lemon.

Add the cucumber cubes, sliced scallion (save some for garnish), Greek yogurt, olive oil, salt, and lemon juice to a blender. Blend until the mixture is very smooth and fluid.

Cover with plastic wrap and chill in the refrigerator for about 6 hours.

Serve the gazpacho in four bowls. Top with the reserved scallion, garnish with parsley leaves, and grind the five peppercorn blend over the top to taste.