It says on the package to mix it with milk and mayo, which is what I have done. I am sure it would be better with buttermilk, but I can't find any around here. In the past I only used those packets to make the dip with sour cream, which is always good, but I can't seem to make the dressing taste right.
And I've noticed that sour cream around here isn't refrigerated, and I've been afraid to try it for fear it won't taste like what I'm used to and I will be disappointed.... silly, I know, but the Old El Paso stuff over here has let me down, and I cried when I got their taco shells and they were all stale and nasty.... lol....