Created on October 25th, 2005
Preheat oven to 250 degrees.
Place popcorn in a very large bowl.
In a medium saucepan over medium heat, melt butter. Stir in brown sugar, corn syrup, and salt. Bring to a boil, stirring constantly. Boil without stirring for 4 minutes.
Remove from heat and stir in soda and vanilla. Slowly pour over popcorn, stirring to coat.
Place in a large baking dish and bake in preheated oven for 1 hour. Stir every 15 minutes.
Remove from oven and let cool completely before breaking into pieces. Store in an airtight container.