In 1-quart saucepan, stir together brown sugar, soy sauce, mustard, rice vinegar, gingerroot and garlic over medium heat. Heat to a light boil. In small bowl, stir cornstarch and water until blended; pour into saucepan. Cook mixture 1 minute, stirring constantly. Heat to boiling; cook 1 minute longer, stirring constantly. Cool 5 minutes.