Follow the manufacturer’s directions for prepping your ice cream maker’s churning bowl so that it is completely chilled prior to starting your ice cream.
Prepare Custard
Combine egg yolks, coconut milk, sugar, and salt in a blender and process until smooth.Pour mixture into a medium sauce pan, and heat over medium low just until steamy. You should see little bubbles forming around the edge of the pan. Do not boil.
Slice the vanilla bean down the middle, and scrape the tiny "vanilla sand" inside into the hot coconut milk mixture. Whisk thoroughly to combine.For more intense vanilla flavor, put the whole cut vanilla bean pod into the hot ice cream mixture, and then fish it out before pouring the ice cream mixture into the ice cream maker.
Continue to cook the coconut milk and vanilla bean mixture until it has thickened to the consistency of a thin custard that will coat the back of a spoon.
Remove the mixture from the heat and whisk in the vodka.The vodka (or vanilla extract) must be added after the mixture is taken off the stove.Refrigerate the mixture for about 2 hours, or until the custard mixture is very cold.
Churn Ice Cream
Pour the custard mixture into ice cream freezer and prepare according to manufacturer’s directions. Churning should take about 30-40 minutes.When done churning, the ice cream will have the consistency of soft serve ice cream.
Serve
For soft-serve style ice cream, serve immediately. For a harder scoopable ice cream, place in the freezer for 2-3 hours. Take out and place on the counter for 10 minutes to soften for serving.
Notes
Vodka-free Alternative: 2 tablespoons of vanilla extract can be substituted in place of the vanilla bean and vodka. Be aware that if you substitute vanilla extract, you are adding roughly twice as much actual alcohol to the mixture as as if you used vodka.