Line a rimmed baking sheet with a nonstick baking mat.
In a medium saucepan, stir together sugar, corn syrup, and bourbon; cook, without stirring, over medium heat until a candy thermometer registers 270°F (132°C). Stir in peanuts. Cook, stirring frequently, until a candy thermometer registers 300°F (149°C).
Remove sugar mixture from heat; working quickly, stir in butter, vanilla, and baking soda until butter is melted and mixture is well combined. (Adding the baking soda will cause the mixture to rapidly bubble.) Pour onto prepared pan; using a large of set spatula, quickly spread into a thin layer. Sprinkle with sea salt Let cool completely.
Break brittle into shards, and store in an airtight container for up to 3 weeks.