Caramel Popcorn

1 C butter
2 C brown sugar
1/2 C corn syrup
1 t salt
1/2 t baking soda
1 t vanilla extract
5 quarts popped popcorn

preheat oven 250. Place popped popcorn in a large bowl, remove kernels. 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 4 minutes. Remove from heat and stir in soda and vanilla. Pour over popcorn, stirring to coat. Place in baking dish and bake in oven 1 hour; stirring every 15 minutes. Remove from oven and let cool completely.