Cut the cucumber in half, lengthwise, and scoop the seeds out with a spoon. Discard the seeds.
1 Cucumber
Grate the cucumber into a bowl, lined with a paper towel or cheese cloth, and mix with a heavy pinch of salt. Set aside for ten minutes to let the water draw out.
Salt and Pepper to Taste
While the cucumber rests, peel and mince the garlic.
2 Cloves Garlic
Mix the yogurt, garlic, olive oil, red wine vinegar and a heavy pinch, each, of salt and pepper in a second bowl or container.
2 C Greek Yogurt, 1/4 C Olive Oil, 1 Tbsp Red Wine Vinegar
Once the cucumber has rested ten minutes, wrap it in the towel or cheese cloth and squeeze out as much of the juice as you can. The juice will not be needed for this dish.
Stir the grated cucumber into the yogurt mixture and chill for at least an hour to allow the flavors to meld.
Give it a taste for salt and pepper before serving.
You can serve tzatziki cold as a dip, topped with a little extra olive oil (optional), or room temperature/warm as a sauce for gyros and meat.