sour cream substitution

i don't always have sour cream lying around and even if i do, i cringe a little when i'm using it because i recognize it isn't the healthiest thing on the planet.  so, my new favorite thing to do is to mix greek yogurt with a little bit of buttermilk.  it works like a charm!  i've used it in stroganoff and tacos and in poppy seed chicken.  no one in my family noticed, either, which is a bonus.