Whisk together all the ingredients except the corn starch. Marinade the meat long enough to flavor and tenderize- 1 hr for young chicken breasts or fish, overnight for round steak and up to 5 days for some game cuts.
BBQ and baste with the marinade. Make a slurry of the starch and a little water and whisk into the marinade. Bring to a boil, stirring as the sauce thickens. Serve with the BBQ'd meat.
Real garlic and ginger only improves this dish. The amount of pepper sauce can be varied from mild to fiery. You can substitute wine, sherry, orange or pineapple juice for some or all of the water to vary the flavor. Pineapple juice has an enzyme that provides additional tenderizing power to the vinegar and mustard.