Dice the chicken breast into 1-inch cubes and season with sea salt and black pepper.
In a small bowl, whisk together coconut aminos, rice vinegar, tomato paste, honey, minced ginger, and minced garlic to create the sauce.
Heat avocado oil in a large skillet over medium-high heat.
Add chicken to the skillet and cook until golden brown and cooked through, about 6-8 minutes, then remove and set aside.
In the same skillet, add the sliced bell peppers, red onion, and pineapple chunks, sautéing for 4-5 minutes until the vegetables are tender-crisp.
Return the chicken to the skillet and pour the sauce over the mixture, stirring constantly until the sauce thickens and coats everything evenly.
In a separate pan or microwave, steam the cauliflower rice until tender.
Serve the sweet and sour chicken immediately over the warm cauliflower rice.