In a saucepan, heat 2 Tablespoons of toasted sesame oil to medium-high heat. Add scallion, garlic and red pepper flakes. Lower heat to medium and continue stirring about 3 – 5 minutes or until garlic starts browning.
Increase heat to high and stir in Soy Sauce, Vinegar and water and bring to a boil.Add dark brown sugar and stir until sugar is dissolved. Lower heat to low and cook for 10 minutes, stirring often.
Makes about 2.5 cups. (Sauce can be refrigerated in air-tight container for several days).