Buttermilk substitutes

[trishka]

I'm looking for a substitute to buttermilk. I came across a recipe for Red Lobster's cheddar biscuits and I really, really want to try them this weekend but I have never used buttermilk and I'm not likely to use it in the future unless this recipe is a hit. Plus, I only need a cup. Any suggestions are appreciated.

[Natalka]

All you have to do is add a Tablespoon full of vinegar to a cup of regular milk, then let it stand for five minutes.
I use this all the time as a sub for buttermilk.

Apparently, you can also use the same amount of lemon juice instead of the vinegar, but I've never tried that.

[trishka]

Awesome, thanks! I have vinegar on hand, not lemon. I kept reading about using cream of tartar and I don't have that nor do I know what that is.