Wash, peel, and halve the cucumbers lengthwise. Scoop out the seeds, then roughly chop the flesh into chunks. Reserve a small handful for garnish.
Combine all ingredients—cucumber, yogurt, olive oil, vinegar, lemon juice, garlic, herbs, salt, pepper, and water—in a high-speed blender.
Blend on high for 60-90 seconds until completely smooth. Stop and scrape down the sides if needed.
Taste and adjust seasoning with salt, vinegar, or lemon juice. If too thick, add a splash more cold water and blend again.
For a silky smooth texture, strain the blended soup through a fine mesh strainer, pressing with a ladle to extract all liquid.
Transfer to an airtight container and refrigerate for at least 2 hours, or overnight, to allow flavors to meld and the soup to chill completely.
Before serving, give the soup a good stir. Taste and adjust seasoning again, as cold can dull flavors.
Ladle into chilled bowls or glasses. Top with garnishes like diced cucumber, fresh herbs, a swirl of yogurt, toasted pumpkin seeds, and a final drizzle of extra virgin olive oil.