Prep the chicken: Freeze the chicken for 15 minutes to firm it up.
Slice thinly against the grain. Pat dry and season lightly with salt and pepper.
Make the sauce: In a bowl, whisk coconut aminos, chicken broth, rice vinegar, sesame oil, low-carb sweetener (if using), and a pinch of red pepper flakes. Sprinkle in xanthan gum while whisking to avoid clumps.
Aim for a light, pourable sauce; it will thicken more in the pan.
Par-cook the broccoli: Steam or microwave broccoli for 1–2 minutes until crisp-tender and bright green. Drain well and set aside.
Stir-fry aromatics: Heat a large skillet or wok over medium-high. Add 1 tablespoon oil.
Cook garlic and ginger for 30 seconds until fragrant. Don’t let them brown. Scoop them out and reserve.
Sear the chicken: Add another tablespoon of oil.
Stir-fry chicken in two batches so it sears instead of steams, about 3–4 minutes per batch, until just cooked through. Return all chicken to the pan along with the aromatics.
Add broccoli and sauce: Toss in the par-cooked broccoli. Pour in the sauce and stir.
Simmer 1–2 minutes until the sauce turns glossy and lightly coats the chicken and broccoli.
Taste and adjust: Add more coconut aminos for salt, a splash of vinegar for brightness, or a pinch of sweetener for balance. Stir in sliced green onions if you like.
Serve: Sprinkle with sesame seeds. Enjoy as is, or spoon over warm cauliflower rice.