Mincemeat Tart, or Mad Magazine Sound Effect?

This week's Resolution Recipe: Ecclefechan Butter Tarts.
"A rich, toffeeish confection of dried fruit, nuts, butter, and dark sugar, they include a surprise spoonful of vinegar, which takes the edge off the sweetness."
( Eck-uhl-feck-en, apparently - easier than it looks. )