In a mixing bowl, add all of the ingredients and stir to combine.
Pour the sauce into a saucepan over medium heat and bring to a simmer. Once simmering, lower the heat and allow the sauce to thicken. While thickening, adjust the crushed red pepper, miso, and mirin (or cooking sake used) until you get your desired balance of flavor.
Remove from the heat and allow the sauce to cool. Use immediately. Or for best flavor, cover the yakiniku sauce and refrigerate for 2 to 3 hours to allow the flavors to meld.