Prep the sauce. In a small bowl, whisk tamari or coconut aminos, vinegar, sesame oil, broth, chili garlic sauce (if using), pepper, and sweetener. If you want a thick sauce, sprinkle in xanthan gum or glucomannan while whisking until just combined. Set aside.
Slice everything thin. Cut protein into bite-size pieces.
Slice veggies into similar sizes so they cook quickly and evenly. Pat protein dry with paper towels to help it sear.
Heat the pan properly. Set a large skillet or wok over medium-high heat. Add 1 tablespoon oil and swirl until shimmering.
Sear the protein. Add the protein in a single layer.
Cook without moving for 1–2 minutes to get color, then stir-fry until just cooked through, 2–4 minutes more. Transfer to a plate.
Stir-fry the veggies. Add remaining oil. Toss in broccoli, peppers, mushrooms, or the firmest veggies first.
Stir-fry 2 minutes, then add quicker-cooking veggies like zucchini, cabbage, snow peas, and bok choy. Cook until crisp-tender, about 3–5 minutes total.
Add aromatics. Push veggies to the sides, add garlic and ginger to the center, and cook 30 seconds until fragrant.
Combine and sauce. Return the protein and any juices to the pan. Pour in the sauce and toss to coat.
Cook 1–2 minutes until glossy and slightly thickened.
Taste and finish. Adjust salt, pepper, heat, or sweetness. Sprinkle sesame seeds and scallions. Serve immediately over cauliflower rice or on its own.