Soak the dry wide rice noodles in a bowl of hot water for 20-30 minutes until flexible but still firm to the bite, then drain and set aside.
In a small mixing bowl, whisk together the coconut aminos, tamari, and fish sauce to create the stir-fry base.
Heat the avocado oil in a large wok or heavy-bottomed skillet over high heat until shimmering.
Add the sliced chicken breast and minced garlic to the pan, stir-frying for 3-4 minutes until the chicken is golden brown and cooked through.
Push the chicken to one side of the wok and crack the egg into the empty space, scrambling it quickly until just set.
Add the chopped Chinese broccoli and the soaked rice noodles to the wok, then immediately pour the sauce mixture over the ingredients.
Toss everything together vigorously for 2 minutes over high heat until the noodles are tender and the sauce has caramelized onto the ingredients.
Sprinkle with white pepper, toss once more, and serve immediately while hot.