Combine all the ingredients in a bowl, and whisk to combine.
1/4 cup soy sauce, 2 tablespoons brown sugar, 1 tablespoon mirin, 1 tablespoon rice wine vinegar, 2 teaspoons sesame oil, 2 teaspoons cornstarch, 1/2 teaspoon Chinese five spice, 2 cloves garlic, 1 piece 1-inch of ginger, minced, 1 teaspoon Szechuan peppercorns