If you're using dried lo mein, boil per package instructions until al dente or 1~2 minutes left to cook. Set aside.
Render the Bacon
Add oil and bacon pieces to a cold wide skillet and turn heat to medium. Let the bacon render slowly, stirring occasionally, until deeply golden and crispy, 6–8 minutes. Remove bacon with a slotted spoon onto a wire rack. Leave a tablespoon or two of the rendered fat in the pan.
Build the Sauce
Add soy sauce, oyster sauce, dark soy sauce, sesame oil, garlic, chili crisp and sugar. Stir to combine. Add chicken stock and bring to a simmer. Let reduce 1–2 minutes until slightly thickened and glossy.
Toss the Lo Mein
Add lo mein directly to the sauce and toss vigorously until every strand is coated and glossy, 1–2 minutes. Add a splash more stock if it tightens too fast. Add your bacon and your green onions and give it a quick toss.
Plate and Finish
Finish with scallions, sesame seeds, and additional crisp drizzle (optional).