I have no idea if the original recipe for this candy is from Ireland, but it was handed down through all of my Irish mothers...who ALL were grand!
Sponge Candy
1 cup sugar
1 cup dark corn syrup
1 Tablespoon vinegar
1 Tablespoon baking soda
Prepare a 9"x9" metal pan by coating the sides and bottom with butter.
Combine sugar, corn syrup, and vinegar in a saucepan.
Cook over medium heat stirring constantly until sugar dissolves.
Continue cooking without stirring until mixture reaches "hard crack stage" when a small bit dropped in cold water becomes brittle.
Remove candy from heat and quickly stir in baking soda. Mix well and quickly as it will foam up.
Pour quickly into buttered pan. Do not spread. Let cool completely.
Dump the cooled, hardened candy onto wax paper and whack it with something hard to break it into pieces, or simply whack it in the pan to break it up. Enjoy!
(note: here in the U.S.A., the pieces are often coated with chocolate for an equally enjoyable treat.)