Gather all your ingredients. Chop the bell peppers, carrots, and green onions into bite-sized pieces. Cook the lo mein noodles according to package instructions until al dente, about 3-4 minutes. Drain and rinse under cold water, then set aside.

In a large skillet or wok, heat 2 tablespoons of sesame oil over medium-high heat. Add the sliced boneless chicken breasts and stir-fry for 6 to 8 minutes until golden brown and fully cooked. Remove and let rest.

In the same skillet, add more oil if needed and toss in the chopped veggies. Stir-fry for 3 to 4 minutes until tender-crisp. Stir frequently to prevent sticking.

Return the cooked chicken to the skillet along with the noodles. Pour in the soy sauce and sesame oil, tossing until combined. Cook for 2-3 minutes until heated through.

Transfer to serving plates and drizzle with more soy sauce or garnish with green onions. Enjoy your Chicken Lo Mein!