Tzatziki is the traditional Greek yogurt dip that's served with pita bread, often as a condiment for souvlaki.
Strain Greek plain yogurt (using cheese cloth or a clean white dish towel in a colander over a bowl, ideally overnight). Yogurt will lose 1/4 to 1/2 of volume, I start with a whole tub.
Peel and grate a large English cucumber. Mix with 1 tbsp white wine vinegar and a large pinch of kosher salt, set aside for a while (at least 15 minutes). Drain using strainer and paper towels, squeeze out all the liquid. You can also let it sit overnight along side the yogurt.
In food processor, combine
1-3 cloves of garlic
3 tbsp good olive oil, ideally Greek
1 tbsp dried Greek wild oregano
small pinch of salt
bit of black pepper
juice and pulp of 2 lemons
some fresh dill
and process until garlic and lemon is completely broken down
Fold everything together in a bold and let sit for a few hours, ideally overnight