Heat a saucepan over medium heat. Add soy sauce, water, and vinegar; cook until heated through, 1 to 2 minutes. Stir in brown sugar, mustard, garlic powder, and ginger; cook until dissolved, about 2 minutes. Remove from heat; let stand until slightly thickened, 3 to 5 minutes.
Another way to make this is to stir together soy sauce, brown sugar, water, vinegar or oil, and spices until sugar is dissolved. All of the sugar may not dissolve well but you can instantly add meat, vegetables, or tofu for at least 10 minutes before cooking it for optimal flavor.
Per Serving: 125 calories;0.1 g fat;
30 g carbohydrates;
1.8 g protein;
0 mg cholesterol;
1072 mg sodium.