In a small bowl, whisk together coconut aminos, rice vinegar, tomato paste, and honey to create the sweet and sour sauce.
Season the diced chicken breast with sea salt and black pepper.
Heat 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 5-6 minutes.
Remove chicken from the pan and set aside.
In the same skillet, add the minced garlic and ginger, sautéing for 30 seconds until fragrant.
Add the red bell pepper, green bell pepper, and snap peas, stir-frying for 3-4 minutes until tender-crisp.
Stir in the pineapple chunks and return the cooked chicken to the skillet.
Pour the sauce over the mixture and toss well to coat, simmering for 1-2 minutes until the sauce thickens slightly.
Serve the stir-fry over the warm cooked brown rice and garnish with sesame seeds.