In a medium saucepan (mine was 3 quarts) over medium heat, combine sugar, corn syrup and vinegar and stir for about 3 minutes or until sugar dissolves and mixture appears shiny and smooth. Continue cooking over medium heat, without stirring, to 300 degrees on a candy thermometer. At exactly 300 degrees, remove from heat and stir in baking soda. Pour into prepared pan and let it fan out, but do not spread. Let the candy cool, then break it into chunks.