In a small bowl, whisk together the coconut aminos, rice vinegar, honey, and arrowroot powder to create the stir-fry sauce.
Season the diced chicken breast evenly with the sea salt and black pepper.
Heat the sesame oil in a large skillet or wok over medium-high heat until shimmering.
Add the chicken to the skillet and sear until golden brown and cooked through, approximately 5 to 7 minutes, then remove from the pan and set aside.
In the same skillet, add the chopped red bell pepper, snap peas, minced ginger, and minced garlic.
Stir-fry the vegetables for 3 to 4 minutes until they are tender-crisp, then stir in the pineapple chunks.
Return the cooked chicken to the skillet and pour the sauce over the mixture.
Toss everything together constantly for 1 to 2 minutes until the sauce thickens into a glossy glaze.
Serve the sweet and sour chicken immediately over the warm cooked brown rice.