Jack in the Box secret sauce
This is the sauce formerly used on the Bonus Jack and the Jumbo Jack before 1999. It's still available in packets at some locations.
or 1/2 tsp onion powder
A1 Steak Sauce
Tabasco or Sriracha, or other hot sauce
Combine vinegar and onion and allow for spices to rehydrate for 30 minutes.
Combine all remaining ingredients with vinegar mixture except xanthan gum (if using).
Slowly sprinkle xanthan into mixture while stirring constantly to avoid lumps
Allow to sit in the refrigerator for 30 minutes for the flavors to develop
The xanthan gum is optional and is there to thicken the mixture and provide a familiar fast food texture. It doesn't add any flavor so is fine without it.