2 c. firmly packed brown sugar (light or dark)
1/4 c. real butter
1 tbsp. vinegar
2 tbsp. boiling water
1 tsp. vanilla

Combine ingredients in a heavy saucepan (add sugar last); bring to a boil very slowly on very low heat (to avoid gritty candy); cook until mixture reaches 300 degree/hard crack stage. Pour into 8x14 inch pan. Cool to lukewarm, then score with sharp knife. Break along scored lines when completely cool.

If candy does not harden, pour it all back into saucepan and cook again. This candy does not do well on humid days.