Step 1

Melt butter in medium saucepan over medium heat. Add onion and cook until softened, about 5 minutes. Add garlic and cook until fragrant, about 30 seconds.

Step 2

Add tomato sauce, cider vinegar, rice vinegar, molasses, Worcestershire sauce, brown sugar, mustard, hot sauce, salt, black pepper, and cayenne and stir to combine. Bring to a boil, then reduce heat to low and simmer until slightly thickened, about 15-20 minutes, stirring occasionally.

Step 3

Transfer sauce to the jar of a blender and blend until smooth. Let cool to room temperature, transfer to a jar and store in refrigerator for up to a month.