Found the secret to that special tangy twang that is hard to get at home - citric acid! Just a bit. The stuff in Fruit-Fresh. I know this recipe will be appreciated when it is just too danged hot to eat a rich ice cream but really, really want something frozen & decadent but refreshing. And I LOVE Greek yogurt & just about anything lemon. I plan to try this one with Splenda instead of the sugar as no cooking is involved. Cook time is freeze time.