Cut the chicken breast into bite-sized cubes and season evenly with sea salt and black pepper.
In a small bowl, whisk together the coconut aminos, rice vinegar, honey, minced ginger, and arrowroot powder to create the stir-fry sauce.
Heat the toasted sesame oil in a large skillet or wok over medium-high heat.
Add the chicken to the skillet and cook for 5-6 minutes until golden brown and cooked through, then remove and set aside.
In the same skillet, add the sliced red onion and bell peppers, sautéing for 3 minutes until crisp-tender.
Stir in the minced garlic and pineapple chunks, cooking for another minute until the pineapple begins to caramelize slightly.
Return the 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.
Serve the sweet and sour chicken immediately over the warm cooked brown rice.