This was handed down through the women in my family. We all love it, but I'm always amazed how many guests beg for the recipe saying that they have never tasted anything like it. The cloves and Worcestershire sauce give it a lovely kick. It keeps really well, so can be made days in advance. It is also a great (and easy) holiday gift.
Stir brown sugar, dried currants, water, vinegar, Worcestershire sauce, butter, salt, black pepper, cloves, and mace together in a saucepan over medium heat, stirring occasionally until butter melts, about 10 minutes. Bring to a boil.
Stir currant jelly into sauce and return to a gentle boil; reduce heat to low and simmer until currents are slightly plump, 5 to 10 minutes.