Cut the chicken breast into bite-sized cubes and season evenly with sea salt and black pepper.
In a small mixing bowl, whisk together the tomato paste, honey, tamari, apple cider vinegar, minced ginger, and minced garlic until smooth.
Heat the avocado oil in a large skillet or wok over medium-high heat.
Add the chicken cubes to the skillet and sauté until golden brown and cooked through, approximately 6 minutes.
Remove the chicken from the skillet and set aside on a plate.
In the same skillet, add the diced red onion and bell peppers, sautéing for 3-4 minutes until they begin to soften but remain crisp.
Stir in the fresh pineapple chunks and cook for another 2 minutes to allow them to caramelize slightly.
Return the cooked chicken to the skillet and pour the prepared sauce over the mixture.
Toss everything together and simmer for 2 minutes until the sauce has thickened and coats the ingredients.
Steam or sauté the cauliflower rice in a separate pan until tender.
Serve the sweet and sour chicken immediately over the warm cauliflower rice.