Combine cream, milk, sugar, and salt in a big heavy pot. Split the vanilla bean lengthwise in half. Scrape seeds into pan with a sharp knife; add bean.
Heat the cream mixture over medium heat, stirring to dissolve the sugar, until bubbles form around the edges of the pan.
Whisk a tiny portion of the heated mixture into the egg yolks in a small bowl; return to the pan, whisking continually.
Cook, stirring frequently, over low heat until the mixture is just thick enough to coat a metal spoon and the temperature hits 180°.
Fill ice cream machine cylinder two-thirds full and freeze according to manufacturer's instructions.