In a small mixing bowl, combine Greek yogurt, olive oil, lemon juice, grated garlic, salt, and pepper. Whisk until smooth.

Slice cucumbers in half lengthwise, then cut into 1/8-inch thick slices.

Finely slice the red onion; rinse it under cold water to mellow its flavor if desired.

In a large salad bowl, mix cucumbers, sliced red onion, and chopped dill. Pour the dressing over and toss gently.

Serve immediately or refrigerate for 15 minutes to allow flavors to meld. Garnish with extra dill if desired.