MAKES ABOUT 1/2 CUP In a small bowl, stir together 1/4 cup gluten-free soy sauce, 3 tablespoons unseasoned rice vinegar, 2 tablespoons water, 1 teaspoon sugar, 1 teaspoon toasted sesame oil, and any of these optional additions: 2 teaspoons finely minced garlic; 1 teaspoon toasted sesame seeds; 1 small green onion, white and green parts, thinly sliced; and 1/2 Fresno or jalapeƱo chile, thinly sliced. Let the sauce rest at room temperature for 1 hour to allow the flavors to develop.