Prep the chicken: Slice chicken into thin strips for quick cooking. Pat dry with paper towels, then season lightly with salt and pepper.
Mix the sauce: In a small bowl, whisk tamari or coconut aminos, rice vinegar, sesame oil, sweetener (if using), and red pepper flakes or sriracha.
If using xanthan gum, sprinkle it in while whisking to avoid clumps. Set aside.
Heat the pan: Place a large skillet or wok over medium-high heat. Add 1 tablespoon of avocado oil and let it get hot until shimmering.
Sear the chicken: Add chicken in a single layer.
Cook 4–6 minutes, stirring occasionally, until golden and just cooked through. Transfer to a plate.
Cook the veggies: Add the remaining 1 tablespoon oil. Toss in broccoli, bell pepper, zucchini, mushrooms, and red onion.
Stir-fry 4–5 minutes until crisp-tender. Season with a pinch of salt.
Add aromatics: Stir in garlic and ginger. Cook 30–45 seconds until fragrant, stirring so they don’t burn.
Bring it together: Return the chicken to the pan.
Pour in the sauce. Toss to coat and cook 1–2 minutes until the sauce slightly thickens and everything is glossy.
Taste and adjust: Add more tamari for salt, vinegar for brightness, or heat for spice. If too salty, a squeeze of lime balances it out.
Serve: Spoon over warm cauliflower rice or shirataki noodles.
Finish with sesame seeds and green onions.