In a sauce pot, add beef stock and bring it to a boil over medium to low heat.
Add all ingredients except for the cornstarch. Let it simmer for 10 minutes.
Cover the pot to trap the flavor as they steam altogether. Adjust little water if needed.
Turn off the heat. Prepare a bowl and a strainer. Then strain the liquid with a bowl under the strainer to reserve the liquid and separate the solid. Do not discard the solid and the liquid. Just set it aside for later.
Heat a clean saucepan and pour-in the filtered mixture. Let it boil and simmer.
Add the diluted cornstarch in water then keep on stirring the sauce until it becomes smooth and thicker.
Turn off the heat and let it cool. Transfer to a sauce container for easy serving.