Sprinkle salt onto chopped garlic. Mash into puree with blade of knife held sideways. Scrape into medium bowl.
Scrape out and discard cucumber seeds. Coarsely grate cucumber.
Squeeze grated cucumber firmly to extract as much juice as possible. Discard juice. Add to bowl with garlic.
Add yogurt, balsamic, olive oil, dill and pepper, stirring together well.
Cover and refrigerate for at least 2 hours for flavors to blend. Add more salt if needed.