The recipe is SAUCE ONLY which can be served over a variety of meatballs:
or Mashed Potatoes.
Ingredients:
Tools：
Procedures:
Heat the vegetable stock, beef stock, heavy cream, soy sauce, and mustard in a sauce pan.
Keep the heated mixture hot but not to boil, and set aside.
Melt butter over medium heat in the pot, and then add in flour.
Keep stirring for 3-4 minutes until the raw flour smell gone.
Gradually add the previous heated mixture into the butter-flour mixture while whisking.
Heat the combined mixture to hot and bubbly.