Pork topping for 4-6 servings (scale as you want):
1 lb ground pork
3 tbsp sambal oelek or 3 pickled medium-hot red chilies
1 tbsp minced garlic
1 1/2 cups water
2 tbsp light soy sauce
2 tbsp dark soy sauce
1 tsp tian mian jiang/sweet wheat sauce

Sauce per serving:
1 tsp melted lard (optional)
2 tbsp chili oil with flakes
2 tbsp light soy sauce
1 tbsp chicken broth
1 tsp zhenjiang black vinegar
1 tsp runny Chinese sesame paste
1/4 tsp or more roasted ground Sichuan pepper
2 tsp thinly sliced green onions

4 oz dried noodles per serving
bok choy and/or fried egg (optional)

1. Make pork topping: Saute pork until beginning to brown and juices are mostly cooked off. Add pickled chilies and garlic, cook, mix with pork. Add water, soy sauces, wheat sauce, simmer about 15 min. Add more water if necessary - you want it to be kinda wet. (It'll probably be wet anyway.)
2. Mix the sauce.

3. Cook noodles, adding bok choy towards the end to cook it too.

4. Each bowl: noodles, sauce, pork topping, bok choy, egg.

Source: Taylor Holliday, The Mala Project, https://blog.themalamarket.com/chengdu-zajiang-noodles-zajiang-mian/