In a small bowl, whisk together the coconut aminos, rice vinegar, tomato paste, honey, grated ginger, and minced garlic to create the sweet and sour sauce.
Season the diced chicken breast evenly with the sea salt and black pepper.
Heat the toasted sesame oil in a large skillet or wok over medium-high heat until shimmering.
Add the chicken to the skillet and sauté until golden brown and cooked through, then remove the chicken from the pan and set aside.
In the same skillet, add the bell peppers and red onion, cooking for 3 minutes until slightly softened but still crisp.
Stir in the fresh pineapple chunks and cook for another minute to caramelize the edges.
Return the chicken to the skillet, pour the prepared sauce over the mixture, and stir constantly for 1-2 minutes until the glaze thickens and coats everything evenly.
Serve the stir-fry immediately over the warm cooked brown rice.