1. In a bowl, toss together popped popcorn (remove any unpopped kernels), cereal and peanuts. Set aside. Butter sides of a heavy 2 quart saucepan.
2. In saucepan, combine apple juice, sugar, corn syrup, vinegar and salt.
3. Cook over medium heat, stirring constantly until sugar dissolves and mixture begins to boil.
4. Cook to hard ball stage (250 degrees Fahrenheit on a candy thermometer).
5. Remove from heat. Pour syrup over popcorn-cereal-peanut mixture; toss to coat.
6. Spread in a buttered 15 1/2 by 10 1/2 by 1-inch baking pan. Cool until hardened.
7. Break into pieces.

Notes

3/4 cup apple wine may be used instead of apple juice.