Prep the chicken: Pat the chicken pieces dry with paper towels.
This helps the coating stick and improves browning.
Set up the coatings: In one bowl, beat the egg. In another, mix almond flour, coconut flour, salt, pepper, and garlic powder.
Coat the chicken: Dip chicken in the egg, let excess drip off, then roll in the flour mixture. Shake off extras so it doesn’t clump.
Brown the chicken: Heat 2 tablespoons avocado oil in a large nonstick skillet over medium-high heat.
Add half the chicken in a single layer. Cook 3–4 minutes per side until golden and mostly cooked through. Transfer to a plate.
Repeat with remaining oil and chicken.
Make the sauce base: In a bowl or measuring cup, whisk tamari (or coconut aminos), rice vinegar, sweetener, sesame oil, garlic, ginger, red pepper flakes, and chicken broth.
Thicken the sauce: Lower heat to medium. Pour the sauce into the same skillet, scraping up browned bits. Sprinkle xanthan gum evenly over the surface while whisking constantly.
Simmer 1–2 minutes until glossy and slightly thickened. If using arrowroot, whisk it with 1 tablespoon cold water first, then stir into the hot sauce and simmer 30–60 seconds.
Combine: Return the chicken and any juices to the skillet. Toss to coat.
Simmer 2–3 minutes until the chicken is cooked through and the sauce clings to each piece.
Finish: Stir in half the sesame seeds and half the green onions. Taste and adjust: add a pinch of salt, a splash more vinegar for tang, or a little extra sweetener if needed.
Serve: Plate with cauliflower rice or broccoli. Sprinkle remaining sesame seeds and green onions on top.