Dice the chicken breast into bite-sized pieces and season evenly with sea salt and black pepper.
In a small bowl, whisk together the coconut aminos, rice vinegar, honey, and arrowroot powder to create the stir-fry sauce.
Heat the sesame oil in a large skillet or wok over medium-high heat until shimmering.
Add the chicken to the skillet and cook until golden brown and cooked through, approximately 5-6 minutes, then remove and set aside.
Add the sliced red onion, bell peppers, and broccoli florets to the same skillet, stir-frying for 3-4 minutes until they are crisp-tender.
Stir in the minced garlic, grated fresh ginger, and pineapple chunks, cooking for another 60 seconds until fragrant.
Return the cooked chicken to the pan and pour the prepared sauce over the mixture.
Toss everything together for 1-2 minutes until the sauce thickens into a glossy glaze that coats all ingredients.
Serve the sweet and sour chicken immediately over the warm cooked brown rice.