In a small bowl, whisk together the coconut aminos, rice vinegar, honey, tomato paste, minced ginger, and minced garlic to create the sauce.
Season the diced chicken breast with sea salt and black pepper.
Heat the avocado oil in a large skillet or wok over medium-high heat.
Add the chicken to the skillet and cook until golden brown and cooked through, about 5-7 minutes, then remove and set aside.
In the same skillet, add the bell peppers and red onion, sautéing until tender-crisp.
Stir in the pineapple chunks and the prepared sauce, tossing to coat the vegetables.
Return the chicken to the skillet and simmer for 2 minutes until the sauce thickens slightly and everything is well combined.
Serve the stir-fry immediately over a bed of warm brown rice.