Place the ketchup, cider vinegar, brown sugar, molasses, Worcestershire sauce, onion powder, pepper, mustard, cumin and 1/4 cup water in a 3-quart saucepan. Bring to a boil, then reduce the heat to a simmer. Cook, uncovered, for 20 to 25 minutes, stirring frequently. Best if made a day in advance. Store in an airtight container in the refrigerator for up to a week.