Shred the cucumber using the large holes on your grater. Put the shredded cucumber in a fine mesh strainer and press out all of the liquid.
Combine the cucumber, yogurt, garlic, red wine vinegar, salt, and pepper in a medium size bowl. Stir, taste, and adjust seasoning if necessary.
Eat as a dip or serve on top of gyros!
Notes
You can make this tzatziki sauce ahead of time and pull it out for a snack or to use on a meal. I find that if I make the sauce a couple of hours before serving the flavors meld and taste even better.