In a small bowl, whisk together the tamari, rice vinegar, honey, toasted sesame oil, and red pepper flakes to create the sauce.
Place the cubed chicken breast in a bowl and toss with arrowroot powder until every piece is lightly and evenly coated.
Heat the avocado oil in a large skillet over medium-high heat until shimmering.
Add the chicken to the skillet and sear for 6-8 minutes, turning occasionally, until the exterior is golden brown and the meat is cooked through.
Remove the chicken from the pan and set aside; add the broccoli florets to the same pan with a splash of water, covering with a lid to steam for 3 minutes.
Remove the lid, add the minced garlic and ginger, and sauté for 1 minute until highly fragrant.
Return the chicken to the skillet and pour the sauce over the mixture, tossing constantly for 1-2 minutes until the sauce thickens into a glossy glaze.
Steam the cauliflower rice separately in a small pan or microwave until tender.
Serve the chicken and broccoli over the cauliflower rice, garnished with sliced green onions and sesame seeds.