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

Trim scallions and cut whites into 1-inch pieces; thinly slice greens. Peel and mince or grate garlic.

Heat a drizzle of oil in a large, preferably nonstick, pan over medium-high heat. Add beef*; using a spatula, press into an even layer. Season with a big pinch of salt and pepper; cook, undisturbed, until browned on bottom, 2-4 minutes. TIP: If there’s excess grease in your pan, carefully pour it out.

Add cabbage and carrot mix and scallion whites; cook, stirring occasionally and breaking up meat into pieces, until veggies are browned and tender and beef is cooked through, 2-4 minutes more.

Stir in stock concentrate, sweet soy glaze, and ¼ cup water (½ cup for 4 servings). Bring to a simmer; cook until thickened, 1 minute. Turn off heat.

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

While noodles cook, in a small microwave-safe bowl, combine garlic, sesame seeds, half the chili flakes, 1 tsp oil, and a pinch of salt (all the chili flakes and 2 tsp oil for 4 servings). (Use fewer chili flakes if you prefer less heat.) Cover tightly with plastic wrap; microwave until fragrant, 30 seconds.

Once noodles are al dente, drain and transfer to pan with beef mixture; toss until thoroughly coated. Taste and season with salt and pepper if desired.

Divide beef lo mein between bowls; drizzle with garlic chili oil and sprinkle with scallion greens. Serve.