Whisk the coconut aminos, rice vinegar, honey, grated ginger, and minced garlic in a small bowl until the honey is fully dissolved.
Cut the chicken breast into uniform 1-inch cubes and season them evenly with sea salt and black pepper.
Heat the avocado oil in a large skillet or wok over medium-high heat until it begins to shimmer.
Add the chicken cubes to the hot pan in a single layer and sear for 5-6 minutes, turning occasionally until golden and cooked through.
Transfer the cooked chicken to a plate and add the bell peppers, red onion, and pineapple chunks to the same skillet.
Sauté the produce for 3-4 minutes until the vegetables are tender-crisp and the pineapple edges are slightly caramelized.
Return the chicken to the skillet and pour the prepared sauce over the mixture, stirring constantly to glaze.
Simmer the stir-fry for 1-2 minutes until the sauce reduces slightly and coats every piece of chicken and vegetable.
Serve the stir-fry over the warm brown rice and sprinkle with sesame seeds for a nutty crunch.