Prepare the brown rice according to package instructions until tender and fluffy.
In a small bowl, whisk together the coconut aminos, apple cider vinegar, tomato paste, honey, arrowroot powder, minced ginger, and minced garlic to create the sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat until shimmering.
Season the diced chicken breast with sea salt and black pepper.
Add the chicken to the hot skillet and sear for 5-6 minutes, stirring occasionally, until golden brown and cooked through.
Toss in the red bell pepper, green bell pepper, and red onion, sautéing for 3-4 minutes until the vegetables are crisp-tender.
Stir in the pineapple chunks and cook for another minute to warm through.
Pour the prepared sauce over the chicken and vegetables, stirring constantly for 1-2 minutes until the sauce thickens and becomes glossy.
Serve the sweet and sour stir-fry immediately over the warm brown rice.