Place quartered cucumbers in a small colander and sprinkle evenly with salt. Allow to drain 30 minutes. Pat dry with paper towels and chop coarsely in food processor. Drain cucumber in colander for an additional 30 minutes. Place cucumber back in food processor with garlic, lemon juice, yogurt, and vinegar. Blend well. Adjust vinegar and salt to taste. Pour in olive oil and blend until ingredients are well combined. Refrigerate until ready to serve.