Dan dan noodles are wheat noodles served in a sauce of sesame paste, soy sauce, rice vinegar, chilli oil, and Sichuan peppercorns, topped with sui mi ya cai (Yibin preserved mustard greens) and a small amount of fried minced pork.
The sauce build
The sauce sits at the bottom of the bowl, not poured over. Toss noodles at the table. Ratio: 2 tbsp sesame paste, 1 tbsp soy sauce, 1 tbsp rice vinegar, 1 tsp chilli oil, half-tsp Sichuan pepper oil, tiny amount of sugar, a ladle of hot noodle water.
Soupy vs dry
Chengdu dan dan mian is traditionally served with a small amount of broth (soupy). The version that became popular internationally — dry-tossed noodles — is a later adaptation. Both are authentic; specify which you prefer when ordering.