1 c. sugar
1 tbsp. cider vinegar
1 c. dark corn syrup
1 tsp. baking soda

Have an 8-inch square pan ready, greased. Stir sugar, syrup and vinegar together in a heavy pan; cook, stirring constantly until boiling. Continue to cook without stirring until mixture reaches 300 degrees on candy thermometer (thread stage). Remove from heat and stir in soda. Mixture will foam up; pour quickly into greased pan without spreading. When cool, break in pieces.