This snack unites salty and sweet in every heaping handful.
Preheat oven to 250 degrees. Place popcorn and nuts in a large bowl. Melt butter in a large heavy saucepan over medium heat. Stir in sugar, corn syrup, and 1/2 teaspoon salt; cook, stirring occasionally, until sugar dissolves. Raise heat to high; bring to a boil without stirring. Cook until mixture reaches 248 degrees on a candy thermometer, 2 to 4 minutes. Remove from heat; stir in baking soda.
Add caramel to popcorn, and stir to coat. Transfer mixture to a rimmed baking sheet.
Bake for 45 minutes, stirring twice. Remove from oven, and immediately sprinkle with 1 teaspoon salt. Let cool. Break into clusters.
Storage: Cooled caramel corn can be stored at room temperature in an airtight container for up to 1 week.
