Pop popcorn according to package directions, and
In 3-quart saucepan, combine brown sugar, corn syrup,
butter, vinegar and salt. Cook and stir until sugar
dissolves. Continue to cook until hard ball stage (250
degrees on candy thermometer).
Pour syrup over popcorn; stir to coat. Add chocolate
pieces and nuts; stir just until mixed. Pour into two
13-by-9-by-2-inch pans, spreading and packing firmly.
In each pan, cut 12 rectangles. Cut each pint of ice
cream into six slices. Sandwich each ice cream slice
between 2 popcorn rectangles.