Make the custard: Whisk the corn, half-and-half, sour cream, sugar and vanilla in a medium saucepan and bring to a simmer over medium heat. Lightly beat the egg yolks in a medium bowl. Slowly whisk about 1/4 cup of the warm corn mixture into the beaten egg yolks, then pour into the saucepan and return to medium heat. Cook, stirring constantly with a wooden spoon, until the mixture thickens and coats the spoon, about 5 minutes.
Transfer the hot custard to a blender and pulse until smooth (keep the filler cap slightly open to let steam escape). Strain the custard through a fine-mesh sieve into a large bowl; discard the solids. Stir often until the mixture cools to room temperature. Lightly press plastic wrap directly against the surface of the custard to prevent a skin from forming. Chill until cold, about 3 hours. (For faster chilling, set the bowl of custard in a bowl of ice water and stir until cold.)
Freeze the cold custard in an ice cream maker according to the manufacturer's directions. Transfer to an airtight container and freeze until firm, 2 to 3 hours.
Scoop the ice cream into bowls. Top with caramel corn or a splash of bourbon, if desired.