A tangy and slightly spicy barbecue sauce perfect for grilling and marinating.
Combine the yellow mustard, sugar, brown sugar, apple cider vinegar, water, chili powder, black pepper, and cayenne pepper in a saucepan.
Stir the mixture thoroughly to ensure all the sugar dissolves evenly.
Bring the mixture to a gentle simmer over medium heat, stirring occasionally.
Keep an eye on the heat to prevent the sauce from boiling over.
Add the soy sauce, butter, and liquid smoke to the saucepan and stir until the butter is melted and fully incorporated.
Adding the butter at this stage gives the sauce a smooth texture.
Simmer the sauce for an additional 10 minutes to blend the flavors.
Taste the sauce and adjust seasoning if necessary.
Allow the sauce to cool completely before transferring it to an airtight container for storage.
Cooling the sauce helps the flavors to meld together better.