In a small bowl, whisk together the tamari, honey, rice vinegar, grated ginger, minced garlic, and arrowroot powder until smooth to create the teriyaki glaze.
Cut the chicken breast into 1-inch bite-sized cubes and season lightly with sea salt and black pepper.
Heat the sesame oil in a large skillet or wok over medium-high heat until shimmering.
Add the chicken cubes to the skillet and sear, stirring occasionally, until the chicken is golden brown and cooked through, approximately 5 to 7 minutes.
Remove the chicken from the skillet and set aside on a plate.
Add the broccoli florets to the same skillet with a tablespoon of water; cover with a lid and steam for 2 to 3 minutes until tender-crisp and bright green.
Return the cooked chicken to the skillet with the broccoli and pour the prepared teriyaki glaze over the top.
Toss everything together for 1 to 2 minutes over medium heat until the sauce thickens and coats the chicken and broccoli beautifully.
Place the warm cooked brown rice in a bowl and top with the teriyaki chicken and broccoli mixture.
Garnish with sliced green onions and sesame seeds before serving.