THIS is how tzatziki should be. NO ONIONS! I've never had tzatziki with onions before but notice that most of the recipes on here seem to include them?! This is simple, delicious and exactly as authentic Greek tzatziki should be. I make this with virtually fat free greek yoghurt and about half the oil and it still comes out beautifully. Keeps in the fridge for 2-3 days, however I suggest you make it the evening before you want it because leaving it overnight really allows the flavours to infuse. Yummy!