In a large bowl, blend first five ingredients with a whisk. Add the vanilla and 1/4 teaspoon salt and continue blending until sugar is dissolved. It should be frothy when you are done.
Chill the ice cream mixture in the refrigerator for 1 hour.
Pour the mixture into a crank freezer or electric ice-cream maker and follow the manufacturer’s directions. If you do not have an ice-cream maker, you can improvise by filling a quart-size zipper-style bag two-thirds full with the buttermilk mixture and zipping it closed, then putting it into a gallon-size zipper-style bag. Hold the mouths of the bags flush while somebody else fills the gallon-size bag with crushed ice and rock salt, in layers. Zip the gallon-size bag closed and begin to massage and shake the bags to achieve the same effect as from a classic ice cream freezer. Keep checking the quart bag to see if your ice cream has frozen sufficiently. This ice cream is generally served at the “soft serve” stage.