In a small saucepan combine the cornstarch, sugar, and the dry mustard; gradually stir in water. Cook, stirring constantly over medium heat till thick and bubbly. Remove from heat. Cover surface with waxed paper. Cool 10 to 15 minutes. Remove waxed paper, stir in the vinegar, catsup, horseradish, Worcestershire. Add garlic. Transfer to storage container, cover and chill.
Remove garlic before using. Makes 11/3 cups (6 calories per tablespoon).