Pat the chicken breast dry with paper towels and cut into uniform bite-sized pieces.
In a medium bowl, toss the chicken with arrowroot powder, sea salt, and black pepper until every piece is lightly and evenly coated.
Heat the avocado oil in a large non-stick skillet or wok over medium-high heat until shimmering.
Add the chicken to the pan in a single layer and sear without moving for 3 minutes, then flip and cook for another 3 minutes until golden and crispy.
Remove the chicken from the pan and set aside on a plate.
Add the broccoli florets and sliced red bell pepper to the same pan, adding a splash of water if needed to steam-sauté for 3-4 minutes until tender-crisp.
While the vegetables cook, whisk together the pineapple juice, coconut aminos, rice vinegar, sesame oil, minced ginger, and minced garlic in a small bowl.
Return the crispy chicken to the pan with the vegetables and pour the sauce over the top.
Toss everything together for 1-2 minutes until the sauce thickens into a glossy glaze that coats the chicken and vegetables.