Bring a large pot of salted water to a rolling boil. Add the lo mein noodles and cook according to package directions until al dente, usually 3 to 4 minutes for fresh noodles or 6 to 8 minutes for dried. Drain immediately and rinse under cold water to stop the cooking process. Set aside.

Heat a large skillet or wok over medium-high heat for 2 minutes. Add cooking oil and swirl to coat. Add sliced chicken in a single layer (work in batches if needed) and cook undisturbed for 2 to 3 minutes until golden brown, then flip and continue cooking for another 3 to 4 minutes until cooked through to 165°F.

Add minced garlic directly to the chicken and stir for 30 seconds until fragrant. Quickly add bell peppers and carrots, tossing everything together. Cook for 3 to 4 minutes, stirring occasionally, until vegetables are tender-crisp with slight char on the edges.

Add the cooked lo mein noodles to the skillet along with soy sauce and sesame oil. Using tongs, toss everything together for 1 to 2 minutes until noodles are evenly coated and heated through. If the mixture looks dry, add a splash of water to loosen.