Making Buttermilk- minus the cow

A lot of recipes call for buttermilk, now in many recipes you can substitute regular milk, but really if a recipe is calling for it, it will really taste the best with buttermilk.  So what do you do if you don't keep buttermilk on hand, and you don't have a cow? You can create it, or more accurately soured milk.  Many of you may know this trick, but it was one my mom told me that I have found useful on many occasions, so I thought I would share here.  By adding lemon juice to regular milk (2%, whole doesn't matter I don't think the fat free would work.....) Anyway. It creates a equivalent for butter milk. The ratio is 1 cup milk to 1 tablespoon of lemon juice.