Peel the cucumber and cut it into quarters lengthwise. Remove the seeds and grate it finely.
Place the grated cucumber on a clean kitchen towel and wring out the excess water.
Add all ingredients into a bowl and stir together.
Season to taste with salt and pepper and serve with bread and/or vegetables. Tastes also amazing with bifteki, gyros, and other spicy meats.
Notes
A lot of greek restaurants add fresh chopped dill and/or mint to the tzatziki. Try a bit first and see how you like it, then add the herbs to your liking. Dried herbs will also work. generally, no other herbs than these are not used.
You can adjust the amount of garlic to your taste.