Cut the chicken breast into bite-sized cubes and season with sea salt and black pepper.
In a small bowl, whisk together the coconut aminos, rice vinegar, honey, tomato paste, and arrowroot powder until smooth to create the sauce.
Heat the avocado oil in a large skillet or wok over medium-high heat.
Add the chicken cubes to the skillet and sauté for 5-6 minutes until golden brown and cooked through, then remove chicken from the pan and set aside.
In the same skillet, add the diced red and green bell peppers along with the red onion, sautéing for 3-4 minutes until tender-crisp.
Stir in the pineapple chunks and cook for another minute to warm through.
Return the chicken to the skillet and pour the sauce over the mixture.
Toss everything together for 1-2 minutes until the sauce thickens and coats the ingredients evenly.
Garnish with sesame seeds before serving.