http://www.elikioliveoil.com/tzatziki.html

Ingredients: 500 grams (1/2 quart) of Greek yoghurt (or natural full, dairy yoghurt), Three garlic cloves, 1/2 cup of olive oil, 1/2 sliced cucumber.

Put the yoghurt in a bowl. Put the garlic through a garlic press and using the edge of a knife, spread the garlic coming our of the press on the yoghurt. Take the cucumber and peal the skin. Slice it thinly, either with a knife or using a salad slicer. Mix the ingredients with a mixer (or a fork) and slowly add the oil. The oil will be absorbed, and when it is done, the tzatzki is ready. Serve with a spoon and a few olives spread on the top.