In a small bowl, whisk together the coconut aminos, rice vinegar, tomato paste, and arrowroot powder until smooth.
Dice the chicken breast into bite-sized pieces and season 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 pan and sauté until golden brown and cooked through, then remove and set aside.
Add the red onion, bell pepper, and snap peas to the same skillet, cooking for 3-4 minutes until tender-crisp.
Stir in the minced garlic and fresh ginger, cooking for 30 seconds until fragrant.
Return the chicken to the pan along with the pineapple chunks and the prepared sauce.
Stir constantly for 1-2 minutes until the sauce thickens and coats everything in a glossy glaze.
Steam the cauliflower rice and serve the sweet and sour chicken immediately over the top.