Toss the sliced chicken with 1 tablespoon of soy sauce and white pepper. Let it sit while you prep everything else.
Heat a wok or large skillet over high heat. Add 1 tablespoon of avocado oil.
Add chicken in a single layer. Let it sear undisturbed for 2–3 minutes until golden on the bottom. Flip and cook another 2–3 minutes until cooked through. Remove to a plate.
If the pan looks dry, add the remaining 1 tablespoon of avocado oil.
Lower the heat slightly. Add sesame oil, scallion whites, garlic, and ginger. Cook 30 seconds until fragrant.
Add shiitakes in a single layer. Let sit 1–2 minutes before stirring. Cook 3–4 minutes until they release moisture and begin to brown.
Once lightly caramelized, add 1–2 teaspoons soy sauce directly to the mushrooms. Let it sizzle 15–20 seconds before stirring to lightly glaze.
Push everything to one side. Add eggs and scramble until just set. Mix together.
Add the slaw mix. Cook over medium-high heat 4–6 minutes, letting it sit occasionally for light browning. You want it softened but still slightly crisp.
Return the chicken to the pan and toss.
Push everything slightly up the sides of the pan. Add hoisin sauce, soy sauce, and rice vinegar directly to the center. Let it bubble for 20–30 seconds, then toss everything together until glossy and evenly coated.
Taste and adjust with a splash more vinegar for brightness or a drizzle of soy for salt if needed.