Drain the excess liquid from the containers of yogurt and measure the yogurt into a medium bowl.
Take the grated cucumber in your hands and squeeze out as much as you can until it is dry. It will shrink to a very small ball.
Pull apart the shreds and add to the yogurt.
Stir in the vinegar, olive oil, garlic, salt, black pepper, and lemon juice and combine well.
Stir in the sour cream.
Cover the bowl and refrigerate for a few hours so the flavors blend. Serve with crispy pita chips or potato wafers.