In a bowl, mix cubed chicken, garlic powder, salt, pepper, fish sauce, and grated ginger until evenly coated.

Boil lo mein noodles according to package directions, undercooking by 1–2 minutes for a firmer texture. Drain and set aside.

Heat 1 tablespoon of cooking oil in a hot skillet or wok over medium-high heat. Add the seasoned chicken and cook for 6–8 minutes, stirring occasionally, until golden brown. In the last 2 minutes, add 1 tablespoon of Szechuan garlic butter and half of the minced garlic, sautéing until fragrant. Remove the chicken from the pan and set aside.

In the same pan, add another tablespoon of cooking oil if needed. Add the remaining minced garlic and grated ginger, sautéing for 1 minute. Toss in cabbage, broccoli, carrots, green onions, mushrooms, and celery. Stir-fry for 5–7 minutes, until the vegetables are tender-crisp.

Return the cooked chicken to the pan with the vegetables. Add the undercooked noodles to the pan. Pour in soy sauce, hoisin sauce, fish sauce, black pepper, and the remaining Szechuan garlic butter. Stir-fry everything together over medium heat for 2–3 minutes, until the noodles are fully cooked and coated in sauce.

Remove from heat and serve immediately.