The signature element of Dan Dan Noodles is the fiery sauce that coats the noodles and pork. In a bowl, combine soy sauce, black vinegar, chili oil, and a touch of sesame oil. Adjust the ingredients to your preferred level of spiciness. Mix the sauce well to ensure all the flavors are evenly distributed. When tossing the noodles, make sure each strand is coated with this delectable sauce, allowing it to soak up the bold and fiery flavors.