If using 1 lb. skinless, boneless chicken thighs (about 4 small), cut into ¼" pieces on a cutting board with a chef’s knife. (To make this process easier, freeze chicken on a baking sheet 30 minutes, then cut chicken when it’s half thawed.) If you’re using 1 lb. ground chicken, skip this step.
Transfer chicken to medium bowl and wash cutting board and knife.
Trim stems from 2 cups shiitake mushrooms (about 5 oz.) and tear into 1" pieces.
Coarsely chop 5 garlic cloves and 4 red or green Thai chiles. Add a pinch of kosher salt and crush with the flat side of knife to a coarse paste (or pound in a mortar and pestle).
Mix ¼ cup tian mian jiang (sweet bean sauce), ¼ cup red miso, ¼ cup black vinegar, 2 Tbsp. dark soy sauce (preferably Pearl River Bridge), and 2 Tbsp. sugar in a small bowl to combine; set sauce aside. (If you don’t have or can’t find tian mian jiang, substitute ¼ cup hoisin sauce and omit the additional sugar.)
Bring a pot of salted water to a boil. Cook 16 oz. fresh or dried thin wheat noodles (such as lo mein lamian, or ramen) according to package directions until al dente. Drain, rinse under cool running water, and set aside.
Meanwhile, heat 1 Tbsp. vegetable oil in a large wok or skillet over medium-high. Cook garlic mixture (the wok should be hot enough that it sizzles immediately), stirring constantly, until softened and fragrant, about 30 seconds. Add chicken and cook, stirring constantly, until pieces are just cooked through and no longer translucent, about 3 minutes. Transfer to a plate along with any juices.
Wipe out wok and reduce heat to medium. Heat another 1 Tbsp. vegetable oil in wok and cook mushrooms, stirring occasionally, until browned and softened, 6–8 minutes.
Increase heat to medium-high. Add chicken mixture and any accumulated juices and reserved sauce and cook, stirring often, until sauce is dark, most of the liquid is evaporated, and everything is coated, about 5 minutes. Add 1 cup water to wok and mix gently to incorporate. Bring to a simmer then reduce heat to low. Simmer uncovered, stirring occasionally, until thick and shiny (it should be about the consistency of gravy), 20–25 minutes.
Coarsely tear a handful of Thai or holy basil and add basil and cooked noodles to chicken; toss gently to coat each strand with sauce.
A note on substitutions: You can use ground chicken instead of thighs, but chopping the thighs yourself will give you meat that’s more succulent and juicy. You can use regular soy sauce instead of dark. And if you don’t have or can’t find tian mian jiang, substitute hoisin sauce and omit the additional sugar.
I suggest that you DO NOT skip the "cup of water" step to make sure that your sauce is balanced and not too salty.
10-12oz of noodles is better, try cooking that much and then adding them slowly to the sauce in the pan, tossing to coat. Stop when you have the noodle to sauce ratio you want.
It is recommended to add some veggies, like shredded carrots, sliced scallions, some cabbage, and snow peas.
