Mine was Czech. I honestly can't remember if she made or used buttermilk, even though they ran Jersey dairy cows. I do remember the fresh whole milk they gave was super creamy.
The Irish pour buttermilk over their oatmeal (steel-cut, of course) and I've tried that to my satisfaction.
My elder daughter gave me a bottle of buttermilk syrup for Christmas. It's nothing like actual buttermilk, unfortunately. It's supposedly for pancakes and such. Not sure if I'll try it again, it was disappointing.
