Whisk the milk with the sugar until the sugar is completely dissolved. Whisk yogurt into the milk mixture.

Open the vanilla bean and scrape out the seeds with a spoon or the edge of a knife. Whisk the vanilla seeds into the milk & yogurt mixture, leaving no lumps.

Pour the whole thing into an electric ice cream maker and prepare according to the manufacturer's directions. This usually takes about 25-30 minutes to freeze.

Store in the freezer a freezer-safe container. Take out for about a half an hour before serving (depending on how warm your house is) in order to soften.