Firehouse Barbecue Sauce
(courtesy of Jason Belton. Makes about 4½ cups of sauce)
3 cups ketchup
1 one-pound box dark brown sugar
½ cup apple cider vinegar
½ cup Worcestershire sauce
1 tablespoon whole celery seed
Combine all ingredients in a saucepan and simmer over low heat for 10 minutes. After completely cooking skinless chicken thighs on the grill, brush the sauce on them and bake on a foil-lined pan for 5 to 10 minutes at 425 degrees F.