Substitutions

A year or so ago, my mom sent me a tub of powdered buttermilk... just add water, presumably?
It's never been opened, so im sure it's still good... if anyone wants it, PM me and pay the postage, and it's yours!

I think it's becoming much more common, I just bought some buttermilk from the miniscule Tesco in Hammersmith tube station, St Ivel brand.
It was with the cream above the milk cages.

The creme fraiche worked beautifully in the beef stroganoff, btw, and I used some egg tagliatelle, which tasted the same as the American style egg noodles generally served with it (though DH thought it would've been better with mash, but he always says that since he doesn't like pasta!) So thanks for the suggestions!

Gonna use what's left to make some ranch dip later with crudité!