In a pan, mix together water, brown sugar, soy sauce, cornstarch and mirin. Stir to dissolve cornstarch before turning on the heat. Bring the mixture to a boil, then reduce to a simmer until the sauce thickens into a glaze. Remove from heat and pour into a ramekin.
½ cup water, ½ cup brown sugar, ¼ cup low sodium soy sauce, 1 teaspoon cornstarch or arrowroot starch, ¼ cup mirin