Buttermilk Substitute

If I have plain yogurt, I'll add a little milk to it and use that.  If I
> don't, I'll use the lemon juice substitution.
>
> I don't care for buttermilk, but it's nice to have it on hand for recipes.
> I buy a half gallon of it, then measure 1/2 cup plus 2 tablespoons into
> baggies.  (The extra two tablespoons compensates for any that stays in the
> measuring cup when I pour it into the baggie, and any that stays in the
> baggie when I pour it into the recipe.)
>
> I lay them flat in a stack on a cookie sheet and freeze them.  Then I can
> stand them up in a stack in the door of the freezer, and thaw whatever I
> need for recipes.