Bring a large pot of salted water to a boil. Wash and dry produce.

Trim and thinly slice scallions, separating whites from greens.

Heat a large dry pan over medium-high heat. Add bacon*; cook, turning occasionally and adjusting heat if browning too quickly, until crispy, 6-10 minutes. (TIP: If your bacon is lean, add a drizzle of oil.) Turn off heat; transfer to a paper-towel-lined plate. Once cool enough to handle, roughly chop. 

Carefully pour bacon fat into a small heatproof bowl (you'll use it in Step 4).

Once water is boiling, add noodles to pot. Cook, stirring occasionally, until al dente, 5-7 minutes. Drain and set aside.

Heat a drizzle of oil in pan used for bacon over medium-high heat. Add scallion whites and bok choy and napa cabbage. Cook, stirring occasionally, until veggies are browned and tender, 2-3 minutes.

Meanwhile, in a second small bowl, combine sweet soy glaze, chili sauce, garlic powder, and 2 TBSP water (4 TBSP for 4 servings).

Add sauce mixture and 1 tsp bacon fat (2 tsp for 4) to pan with veggies. (TIP: Add more reserved bacon fat for a richer flavor!) Cook, stirring, until veggies are coated and sauce is warmed through, 30-60 seconds. Remove from heat. 

Add drained noodles and half the bacon to pan with veggies; toss to coat. Taste and season with salt and pepper.

Divide lo mein between bowls. Top with sesame seeds, scallion greens, and remaining bacon. Serve.