you put some fast tunes on radio when milking cows, not too fast or long, or you will have butter, but a bit slower, and shorter songs and they sway to the buttermilk stage. Glad you didn't ask about "non-fat dry milk"...
If you need it in a rush, add 1tbs. per 1 cup of milk and stir . Let set for 2 or 3 minutes and you have instant buttermilk!
This is a Simple Dialog Demo.