Your brief description sounds like a dish we do often...
Schweinbraten... I don't have my recipe at hand, but this is very similar:
http://www.recipezaar.com/170477
We thickly slice potatoes and add to the
braten marinade for the last day of marinating or so. The meat, as the recipe suggests, is best when grilled (on a grill, ya'll call it barbecue, no?) and the potatoes are placed in aluminum foil pouch with some of the marinade and grill as well... Best of luck!