Pat the chicken breast dry with a paper towel and cut into 1-inch bite-sized cubes.
In a medium bowl, toss the chicken cubes with the arrowroot powder, sea salt, and black pepper until each piece is evenly coated.
Heat the avocado oil in a large skillet over medium-high heat until it begins to shimmer.
Add the chicken to the skillet in a single layer and sear undisturbed for 3-4 minutes to develop a golden, crispy crust.
Flip the chicken pieces and cook for an additional 3 minutes until they are golden brown on all sides.
Add the broccoli florets and 2 tablespoons of water to the pan, then immediately cover with a lid to steam for 2-3 minutes.
Remove the lid and stir in the minced garlic, grated ginger, and coconut aminos.
Stir-fry everything together for 1-2 minutes until the sauce reduces and forms a thick, glossy glaze over the chicken and broccoli.
Transfer to a plate and garnish with sesame seeds before serving.