Prep everything first. Thinly slice the chicken and vegetables so they cook fast and evenly. Mince garlic and ginger. Stir fry moves quickly, so having everything ready makes a big difference.

Make the sauce. In a small bowl, whisk tamari or coconut aminos, rice vinegar, sesame oil, keto sweetener, and red pepper flakes if using. Taste and adjust salt or sweetness. If you plan to thicken, sprinkle in xanthan gum and whisk well to avoid clumps.

Heat the pan properly. Use a large wok or a wide skillet. Add 1 tablespoon oil and heat over medium-high until shimmering. A hot pan gives you good sear and prevents sogginess.

Cook the chicken in batches. Season sliced chicken lightly with salt and pepper. Add half to the pan, spread it out, and let it sear for 2–3 minutes before stirring. Cook until just cooked through, 4–5 minutes total. Transfer to a plate and repeat with remaining chicken, adding a little more oil if needed.

Stir fry the vegetables. Add another tablespoon of oil. Toss in onions and mushrooms first; cook 2 minutes. Add broccoli and bell pepper; cook 2–3 minutes more. Add zucchini and cabbage last since they soften quickly; cook 1–2 minutes. Vegetables should be crisp-tender.

Add aromatics. Push vegetables to the sides. Add a small splash of oil if the pan looks dry. Stir in garlic and ginger; cook 30 seconds until fragrant.

Bring it together. Return chicken and any juices to the pan. Pour in the sauce. Toss everything to coat. Let it bubble for 1–2 minutes so flavors meld and the sauce slightly thickens.

Finish and serve. Turn off heat. Sprinkle in green onions and sesame seeds. Taste and adjust with a splash of tamari, vinegar, or a pinch of sweetener if needed. Serve over warm cauliflower rice or zucchini noodles.