Line a baking sheet with parchment paper or lightly butter it. Set aside.
In a medium saucepan over medium heat, combine sugar, corn syrup, water, and salt. Stir until the sugar is fully dissolved.
Once the mixture begins to boil, stop stirring. Allow it to cook undisturbed until it reaches a deep amber color and 300°F on a candy thermometer.
Remove the pan from heat. Carefully stir in the butter and vanilla until fully combined.
Quickly stir in the baking soda. The mixture will foam and lighten in texture—this is normal.
Immediately pour the candy onto the prepared baking sheet. Tilt the pan or use a spatula to spread it into a thin layer.
Let the candy cool at room temperature for 30 minutes, or until fully set.
Cut into small pieces and wrap each piece in parchment paper.
