In a large stockpot, place both racks of ribs; add enough water to cover ribs.
Add marinade, bay leaves and onion. Bring mixture to a boil over high heat. (This will create foam on top.)
Reduce to medium-low heat; simmer 45 minutes or until ribs are just tender.
Remove ribs from cooking liquid, drain on rimmed baking sheet.
Heat grill to medium heat (about 350 degrees F.)
In small mixing bowl, stir together the barbecue sauce and brown sugar. Brush over both sides of ribs.
Place ribs on grill, bone side down, close lid. Grill for 7 minutes, turn and grill 7 minutes more.
