Pat the chicken breast dry and cut into 1-inch cubes, then season with sea salt and black pepper.
In a small bowl, whisk together the coconut aminos, rice vinegar, tomato paste, honey, minced ginger, and minced garlic to create the sauce.
Heat avocado 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, about 5-6 minutes, then remove and set aside.
In the same skillet, add the bell peppers and onion, sautéing for 3-4 minutes until crisp-tender.
Stir in the pineapple chunks and the prepared sauce, tossing to combine and allowing the sauce to thicken slightly for 1-2 minutes.
Return the chicken to the pan, drizzle with toasted sesame oil, and toss until everything is beautifully glazed.
Serve the stir-fry immediately over steamed cauliflower rice.